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<title>basicTypes/MkId.lhs</title>
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%
% (c) The University of Glasgow 2006
% (c) The AQUA Project, Glasgow University, 1998
%
This module contains definitions for the IdInfo for things that
have a standard form, namely:
- data constructors
- record selectors
- method and superclass selectors
- primitive operations
\begin{code}
<pre><a name="line-1"></a><span class='hs-comment'>{-# OPTIONS -fno-warn-missing-signatures #-}</span>
<a name="line-2"></a><span class='hs-comment'>-- The above warning supression flag is a temporary kludge.</span>
<a name="line-3"></a><span class='hs-comment'>-- While working on this module you are encouraged to remove it and fix</span>
<a name="line-4"></a><span class='hs-comment'>-- any warnings in the module. See</span>
<a name="line-5"></a><span class='hs-comment'>-- <<a href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings">http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings</a>></span>
<a name="line-6"></a><span class='hs-comment'>-- for details</span>
<a name="line-7"></a>
<a name="line-8"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>MkId</span> <span class='hs-layout'>(</span>
<a name="line-9"></a> <span class='hs-varid'>mkDictFunId</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkDefaultMethodId</span><span class='hs-layout'>,</span>
<a name="line-10"></a> <span class='hs-varid'>mkDictSelId</span><span class='hs-layout'>,</span>
<a name="line-11"></a>
<a name="line-12"></a> <span class='hs-varid'>mkDataConIds</span><span class='hs-layout'>,</span>
<a name="line-13"></a> <span class='hs-varid'>mkPrimOpId</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkFCallId</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkTickBoxOpId</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkBreakPointOpId</span><span class='hs-layout'>,</span>
<a name="line-14"></a>
<a name="line-15"></a> <span class='hs-varid'>mkReboxingAlt</span><span class='hs-layout'>,</span> <span class='hs-varid'>wrapNewTypeBody</span><span class='hs-layout'>,</span> <span class='hs-varid'>unwrapNewTypeBody</span><span class='hs-layout'>,</span>
<a name="line-16"></a> <span class='hs-varid'>wrapFamInstBody</span><span class='hs-layout'>,</span> <span class='hs-varid'>unwrapFamInstScrut</span><span class='hs-layout'>,</span>
<a name="line-17"></a> <span class='hs-varid'>mkUnpackCase</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkProductBox</span><span class='hs-layout'>,</span>
<a name="line-18"></a>
<a name="line-19"></a> <span class='hs-comment'>-- And some particular Ids; see below for why they are wired in</span>
<a name="line-20"></a> <span class='hs-varid'>wiredInIds</span><span class='hs-layout'>,</span> <span class='hs-varid'>ghcPrimIds</span><span class='hs-layout'>,</span>
<a name="line-21"></a> <span class='hs-varid'>unsafeCoerceId</span><span class='hs-layout'>,</span> <span class='hs-varid'>realWorldPrimId</span><span class='hs-layout'>,</span> <span class='hs-varid'>voidArgId</span><span class='hs-layout'>,</span> <span class='hs-varid'>nullAddrId</span><span class='hs-layout'>,</span> <span class='hs-varid'>seqId</span><span class='hs-layout'>,</span>
<a name="line-22"></a> <span class='hs-varid'>lazyId</span><span class='hs-layout'>,</span> <span class='hs-varid'>lazyIdKey</span><span class='hs-layout'>,</span>
<a name="line-23"></a>
<a name="line-24"></a> <span class='hs-varid'>mkRuntimeErrorApp</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkImpossibleExpr</span><span class='hs-layout'>,</span>
<a name="line-25"></a> <span class='hs-varid'>rEC_CON_ERROR_ID</span><span class='hs-layout'>,</span> <span class='hs-varid'>iRREFUT_PAT_ERROR_ID</span><span class='hs-layout'>,</span> <span class='hs-varid'>rUNTIME_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-26"></a> <span class='hs-varid'>nON_EXHAUSTIVE_GUARDS_ERROR_ID</span><span class='hs-layout'>,</span> <span class='hs-varid'>nO_METHOD_BINDING_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-27"></a> <span class='hs-varid'>pAT_ERROR_ID</span><span class='hs-layout'>,</span> <span class='hs-varid'>eRROR_ID</span><span class='hs-layout'>,</span> <span class='hs-varid'>rEC_SEL_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-28"></a>
<a name="line-29"></a> <span class='hs-varid'>unsafeCoerceName</span>
<a name="line-30"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-31"></a>
<a name="line-32"></a><span class='hs-cpp'>#include "HsVersions.h"</span>
<a name="line-33"></a>
<a name="line-34"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Rules</span>
<a name="line-35"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>TysPrim</span>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>TysWiredIn</span>
<a name="line-37"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>PrelRules</span>
<a name="line-38"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Type</span>
<a name="line-39"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Coercion</span>
<a name="line-40"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>TcType</span>
<a name="line-41"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>CoreUtils</span> <span class='hs-layout'>(</span> <span class='hs-varid'>exprType</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkCoerce</span> <span class='hs-layout'>)</span>
<a name="line-42"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>CoreUnfold</span>
<a name="line-43"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Literal</span>
<a name="line-44"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>TyCon</span>
<a name="line-45"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Class</span>
<a name="line-46"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>VarSet</span>
<a name="line-47"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Name</span>
<a name="line-48"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>PrimOp</span>
<a name="line-49"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>ForeignCall</span>
<a name="line-50"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>DataCon</span>
<a name="line-51"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Id</span>
<a name="line-52"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Var</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Var</span><span class='hs-layout'>,</span> <span class='hs-conid'>TyVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkCoVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkExportedLocalVar</span> <span class='hs-layout'>)</span>
<a name="line-53"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>IdInfo</span>
<a name="line-54"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>NewDemand</span>
<a name="line-55"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>CoreSyn</span>
<a name="line-56"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Unique</span>
<a name="line-57"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>PrelNames</span>
<a name="line-58"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>BasicTypes</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span> <span class='hs-conid'>SuccessFlag</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span> <span class='hs-layout'>)</span>
<a name="line-59"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Util</span>
<a name="line-60"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Outputable</span>
<a name="line-61"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>FastString</span>
<a name="line-62"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>ListSetOps</span>
<a name="line-63"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Module</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{Wired in Ids}
%* *
%************************************************************************
Note [Wired-in Ids]
~~~~~~~~~~~~~~~~~~~
There are several reasons why an Id might appear in the wiredInIds:
(1) The ghcPrimIds are wired in because they can't be defined in
Haskell at all, although the can be defined in Core. They have
compulsory unfoldings, so they are always inlined and they have
no definition site. Their home module is GHC.Prim, so they
also have a description in primops.txt.pp, where they are called
'pseudoops'.
(2) The 'error' function, eRROR_ID, is wired in because we don't yet have
a way to express in an interface file that the result type variable
is 'open'; that is can be unified with an unboxed type
[The interface file format now carry such information, but there's
no way yet of expressing at the definition site for these
error-reporting functions that they have an 'open'
result type. -- sof 1/99]
(3) Other error functions (rUNTIME_ERROR_ID) are wired in (a) because
the desugarer generates code that mentiones them directly, and
(b) for the same reason as eRROR_ID
(4) lazyId is wired in because the wired-in version overrides the
strictness of the version defined in GHC.Base
In cases (2-4), the function has a definition in a library module, and
can be called; but the wired-in version means that the details are
never read from that module's interface file; instead, the full definition
is right here.
\begin{code}
<pre><a name="line-1"></a><a name="wiredInIds"></a><span class='hs-definition'>wiredInIds</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span>
<a name="line-2"></a><span class='hs-definition'>wiredInIds</span>
<a name="line-3"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span>
<a name="line-4"></a>
<a name="line-5"></a> <span class='hs-varid'>eRROR_ID</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- This one isn't used anywhere else in the compiler</span>
<a name="line-6"></a> <span class='hs-comment'>-- But we still need it in wiredInIds so that when GHC</span>
<a name="line-7"></a> <span class='hs-comment'>-- compiles a program that mentions 'error' we don't</span>
<a name="line-8"></a> <span class='hs-comment'>-- import its type from the interface file; we just get</span>
<a name="line-9"></a> <span class='hs-comment'>-- the Id defined here. Which has an 'open-tyvar' type.</span>
<a name="line-10"></a>
<a name="line-11"></a> <span class='hs-varid'>rUNTIME_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-12"></a> <span class='hs-varid'>iRREFUT_PAT_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-13"></a> <span class='hs-varid'>nON_EXHAUSTIVE_GUARDS_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-14"></a> <span class='hs-varid'>nO_METHOD_BINDING_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-15"></a> <span class='hs-varid'>pAT_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-16"></a> <span class='hs-varid'>rEC_CON_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-17"></a> <span class='hs-varid'>rEC_SEL_ERROR_ID</span><span class='hs-layout'>,</span>
<a name="line-18"></a>
<a name="line-19"></a> <span class='hs-varid'>lazyId</span>
<a name="line-20"></a> <span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span> <span class='hs-varid'>ghcPrimIds</span>
<a name="line-21"></a>
<a name="line-22"></a><a name="ghcPrimIds"></a><span class='hs-comment'>-- These Ids are exported from GHC.Prim</span>
<a name="line-23"></a><span class='hs-definition'>ghcPrimIds</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span>
<a name="line-24"></a><span class='hs-definition'>ghcPrimIds</span>
<a name="line-25"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span> <span class='hs-comment'>-- These can't be defined in Haskell, but they have</span>
<a name="line-26"></a> <span class='hs-comment'>-- perfectly reasonable unfoldings in Core</span>
<a name="line-27"></a> <span class='hs-varid'>realWorldPrimId</span><span class='hs-layout'>,</span>
<a name="line-28"></a> <span class='hs-varid'>unsafeCoerceId</span><span class='hs-layout'>,</span>
<a name="line-29"></a> <span class='hs-varid'>nullAddrId</span><span class='hs-layout'>,</span>
<a name="line-30"></a> <span class='hs-varid'>seqId</span>
<a name="line-31"></a> <span class='hs-keyglyph'>]</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{Data constructors}
%* *
%************************************************************************
The wrapper for a constructor is an ordinary top-level binding that evaluates
any strict args, unboxes any args that are going to be flattened, and calls
the worker.
We're going to build a constructor that looks like:
data (Data a, C b) => T a b = T1 !a !Int b
T1 = /\ a b ->
\d1::Data a, d2::C b ->
\p q r -> case p of { p ->
case q of { q ->
Con T1 [a,b] [p,q,r]}}
Notice that
* d2 is thrown away --- a context in a data decl is used to make sure
one *could* construct dictionaries at the site the constructor
is used, but the dictionary isn't actually used.
* We have to check that we can construct Data dictionaries for
the types a and Int. Once we've done that we can throw d1 away too.
* We use (case p of q -> ...) to evaluate p, rather than "seq" because
all that matters is that the arguments are evaluated. "seq" is
very careful to preserve evaluation order, which we don't need
to be here.
You might think that we could simply give constructors some strictness
info, like PrimOps, and let CoreToStg do the let-to-case transformation.
But we don't do that because in the case of primops and functions strictness
is a *property* not a *requirement*. In the case of constructors we need to
do something active to evaluate the argument.
Making an explicit case expression allows the simplifier to eliminate
it in the (common) case where the constructor arg is already evaluated.
Note [Wrappers for data instance tycons]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the case of data instances, the wrapper also applies the coercion turning
the representation type into the family instance type to cast the result of
the wrapper. For example, consider the declarations
data family Map k :: * -> *
data instance Map (a, b) v = MapPair (Map a (Pair b v))
The tycon to which the datacon MapPair belongs gets a unique internal
name of the form :R123Map, and we call it the representation tycon.
In contrast, Map is the family tycon (accessible via
tyConFamInst_maybe). A coercion allows you to move between
representation and family type. It is accessible from :R123Map via
tyConFamilyCoercion_maybe and has kind
Co123Map a b v :: {Map (a, b) v ~ :R123Map a b v}
The wrapper and worker of MapPair get the types
-- Wrapper
$WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
$WMapPair a b v = MapPair a b v `cast` sym (Co123Map a b v)
-- Worker
MapPair :: forall a b v. Map a (Map a b v) -> :R123Map a b v
This coercion is conditionally applied by wrapFamInstBody.
It's a bit more complicated if the data instance is a GADT as well!
data instance T [a] where
T1 :: forall b. b -> T [Maybe b]
Hence
Co7T a :: T [a] ~ :R7T a
Now we want
-- Wrapper
$WT1 :: forall b. b -> T [Maybe b]
$WT1 b v = T1 (Maybe b) b (Maybe b) v
`cast` sym (Co7T (Maybe b))
-- Worker
T1 :: forall c b. (c ~ Maybe b) => b -> :R7T c
\begin{code}
<pre><a name="line-1"></a><a name="mkDataConIds"></a><span class='hs-definition'>mkDataConIds</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DataCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DataConIds</span>
<a name="line-2"></a><span class='hs-definition'>mkDataConIds</span> <span class='hs-varid'>wrap_name</span> <span class='hs-varid'>wkr_name</span> <span class='hs-varid'>data_con</span>
<a name="line-3"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-comment'>-- Newtype, only has a worker</span>
<a name="line-4"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DCIds</span> <span class='hs-conid'>Nothing</span> <span class='hs-varid'>nt_work_id</span>
<a name="line-5"></a>
<a name="line-6"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>any</span> <span class='hs-varid'>isMarkedStrict</span> <span class='hs-varid'>all_strict_marks</span> <span class='hs-comment'>-- Algebraic, needs wrapper</span>
<a name="line-7"></a> <span class='hs-varop'>||</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>null</span> <span class='hs-varid'>eq_spec</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- NB: LoadIface.ifaceDeclSubBndrs</span>
<a name="line-8"></a> <span class='hs-varop'>||</span> <span class='hs-varid'>isFamInstTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-comment'>-- depends on this test</span>
<a name="line-9"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DCIds</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>alg_wrap_id</span><span class='hs-layout'>)</span> <span class='hs-varid'>wrk_id</span>
<a name="line-10"></a>
<a name="line-11"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-comment'>-- Algebraic, no wrapper</span>
<a name="line-12"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DCIds</span> <span class='hs-conid'>Nothing</span> <span class='hs-varid'>wrk_id</span>
<a name="line-13"></a> <span class='hs-keyword'>where</span>
<a name="line-14"></a> <span class='hs-layout'>(</span><span class='hs-varid'>univ_tvs</span><span class='hs-layout'>,</span> <span class='hs-varid'>ex_tvs</span><span class='hs-layout'>,</span> <span class='hs-varid'>eq_spec</span><span class='hs-layout'>,</span>
<a name="line-15"></a> <span class='hs-varid'>eq_theta</span><span class='hs-layout'>,</span> <span class='hs-varid'>dict_theta</span><span class='hs-layout'>,</span> <span class='hs-varid'>orig_arg_tys</span><span class='hs-layout'>,</span> <span class='hs-varid'>res_ty</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConFullSig</span> <span class='hs-varid'>data_con</span>
<a name="line-16"></a> <span class='hs-varid'>tycon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConTyCon</span> <span class='hs-varid'>data_con</span> <span class='hs-comment'>-- The representation TyCon (not family)</span>
<a name="line-17"></a>
<a name="line-18"></a> <span class='hs-comment'>----------- Worker (algebraic data types only) --------------</span>
<a name="line-19"></a> <span class='hs-comment'>-- The *worker* for the data constructor is the function that</span>
<a name="line-20"></a> <span class='hs-comment'>-- takes the representation arguments and builds the constructor.</span>
<a name="line-21"></a> <span class='hs-varid'>wrk_id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>DataConWorkId</span> <span class='hs-varid'>data_con</span><span class='hs-layout'>)</span> <span class='hs-varid'>wkr_name</span>
<a name="line-22"></a> <span class='hs-layout'>(</span><span class='hs-varid'>dataConRepType</span> <span class='hs-varid'>data_con</span><span class='hs-layout'>)</span> <span class='hs-varid'>wkr_info</span>
<a name="line-23"></a>
<a name="line-24"></a> <span class='hs-varid'>wkr_arity</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConRepArity</span> <span class='hs-varid'>data_con</span>
<a name="line-25"></a> <span class='hs-varid'>wkr_info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
<a name="line-26"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-varid'>wkr_arity</span>
<a name="line-27"></a> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>wkr_sig</span>
<a name="line-28"></a> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>evaldUnfolding</span> <span class='hs-comment'>-- Record that it's evaluated,</span>
<a name="line-29"></a> <span class='hs-comment'>-- even if arity = 0</span>
<a name="line-30"></a>
<a name="line-31"></a> <span class='hs-varid'>wkr_sig</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkStrictSig</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopDmdType</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>wkr_arity</span> <span class='hs-varid'>topDmd</span><span class='hs-layout'>)</span> <span class='hs-varid'>cpr_info</span><span class='hs-layout'>)</span>
<a name="line-32"></a> <span class='hs-comment'>-- Note [Data-con worker strictness]</span>
<a name="line-33"></a> <span class='hs-comment'>-- Notice that we do *not* say the worker is strict</span>
<a name="line-34"></a> <span class='hs-comment'>-- even if the data constructor is declared strict</span>
<a name="line-35"></a> <span class='hs-comment'>-- e.g. data T = MkT !(Int,Int)</span>
<a name="line-36"></a> <span class='hs-comment'>-- Why? Because the *wrapper* is strict (and its unfolding has case</span>
<a name="line-37"></a> <span class='hs-comment'>-- expresssions that do the evals) but the *worker* itself is not.</span>
<a name="line-38"></a> <span class='hs-comment'>-- If we pretend it is strict then when we see</span>
<a name="line-39"></a> <span class='hs-comment'>-- case x of y -> $wMkT y</span>
<a name="line-40"></a> <span class='hs-comment'>-- the simplifier thinks that y is "sure to be evaluated" (because</span>
<a name="line-41"></a> <span class='hs-comment'>-- $wMkT is strict) and drops the case. No, $wMkT is not strict.</span>
<a name="line-42"></a> <span class='hs-comment'>--</span>
<a name="line-43"></a> <span class='hs-comment'>-- When the simplifer sees a pattern </span>
<a name="line-44"></a> <span class='hs-comment'>-- case e of MkT x -> ...</span>
<a name="line-45"></a> <span class='hs-comment'>-- it uses the dataConRepStrictness of MkT to mark x as evaluated;</span>
<a name="line-46"></a> <span class='hs-comment'>-- but that's fine... dataConRepStrictness comes from the data con</span>
<a name="line-47"></a> <span class='hs-comment'>-- not from the worker Id.</span>
<a name="line-48"></a>
<a name="line-49"></a> <span class='hs-varid'>cpr_info</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isProductTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-varop'>&&</span>
<a name="line-50"></a> <span class='hs-varid'>isDataTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-varop'>&&</span>
<a name="line-51"></a> <span class='hs-varid'>wkr_arity</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span> <span class='hs-varop'>&&</span>
<a name="line-52"></a> <span class='hs-varid'>wkr_arity</span> <span class='hs-varop'><=</span> <span class='hs-varid'>mAX_CPR_SIZE</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>retCPR</span>
<a name="line-53"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>TopRes</span>
<a name="line-54"></a> <span class='hs-comment'>-- RetCPR is only true for products that are real data types;</span>
<a name="line-55"></a> <span class='hs-comment'>-- that is, not unboxed tuples or [non-recursive] newtypes</span>
<a name="line-56"></a>
<a name="line-57"></a> <span class='hs-comment'>----------- Workers for newtypes --------------</span>
<a name="line-58"></a> <span class='hs-varid'>nt_work_id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>DataConWrapId</span> <span class='hs-varid'>data_con</span><span class='hs-layout'>)</span> <span class='hs-varid'>wkr_name</span> <span class='hs-varid'>wrap_ty</span> <span class='hs-varid'>nt_work_info</span>
<a name="line-59"></a> <span class='hs-varid'>nt_work_info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span> <span class='hs-comment'>-- The NoCaf-ness is set by noCafIdInfo</span>
<a name="line-60"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-num'>1</span> <span class='hs-comment'>-- Arity 1</span>
<a name="line-61"></a> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>newtype_unf</span>
<a name="line-62"></a> <span class='hs-varid'>id_arg1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTemplateLocal</span> <span class='hs-num'>1</span> <span class='hs-layout'>(</span><span class='hs-varid'>head</span> <span class='hs-varid'>orig_arg_tys</span><span class='hs-layout'>)</span>
<a name="line-63"></a> <span class='hs-varid'>newtype_unf</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ASSERT2</span><span class='hs-layout'>(</span> <span class='hs-varid'>isVanillaDataCon</span> <span class='hs-varid'>data_con</span> <span class='hs-varop'>&&</span>
<a name="line-64"></a> <span class='hs-varid'>isSingleton</span> <span class='hs-varid'>orig_arg_tys</span><span class='hs-layout'>,</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>data_con</span> <span class='hs-layout'>)</span>
<a name="line-65"></a> <span class='hs-comment'>-- Note [Newtype datacons]</span>
<a name="line-66"></a> <span class='hs-varid'>mkCompulsoryUnfolding</span> <span class='hs-varop'>$</span>
<a name="line-67"></a> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>wrap_tvs</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Lam</span> <span class='hs-varid'>id_arg1</span> <span class='hs-varop'>$</span>
<a name="line-68"></a> <span class='hs-varid'>wrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>res_ty_args</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>id_arg1</span><span class='hs-layout'>)</span>
<a name="line-69"></a>
<a name="line-70"></a>
<a name="line-71"></a> <span class='hs-comment'>----------- Wrapper --------------</span>
<a name="line-72"></a> <span class='hs-comment'>-- We used to include the stupid theta in the wrapper's args</span>
<a name="line-73"></a> <span class='hs-comment'>-- but now we don't. Instead the type checker just injects these</span>
<a name="line-74"></a> <span class='hs-comment'>-- extra constraints where necessary.</span>
<a name="line-75"></a> <span class='hs-varid'>wrap_tvs</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>univ_tvs</span> <span class='hs-varop'>`minusList`</span> <span class='hs-varid'>map</span> <span class='hs-varid'>fst</span> <span class='hs-varid'>eq_spec</span><span class='hs-layout'>)</span> <span class='hs-varop'>++</span> <span class='hs-varid'>ex_tvs</span>
<a name="line-76"></a> <span class='hs-varid'>res_ty_args</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>substTyVars</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopTvSubst</span> <span class='hs-varid'>eq_spec</span><span class='hs-layout'>)</span> <span class='hs-varid'>univ_tvs</span>
<a name="line-77"></a> <span class='hs-varid'>eq_tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPredTys</span> <span class='hs-varid'>eq_theta</span>
<a name="line-78"></a> <span class='hs-varid'>dict_tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPredTys</span> <span class='hs-varid'>dict_theta</span>
<a name="line-79"></a> <span class='hs-varid'>wrap_ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-varid'>wrap_tvs</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mkFunTys</span> <span class='hs-varid'>eq_tys</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mkFunTys</span> <span class='hs-varid'>dict_tys</span> <span class='hs-varop'>$</span>
<a name="line-80"></a> <span class='hs-varid'>mkFunTys</span> <span class='hs-varid'>orig_arg_tys</span> <span class='hs-varop'>$</span> <span class='hs-varid'>res_ty</span>
<a name="line-81"></a> <span class='hs-comment'>-- NB: watch out here if you allow user-written equality </span>
<a name="line-82"></a> <span class='hs-comment'>-- constraints in data constructor signatures</span>
<a name="line-83"></a>
<a name="line-84"></a> <span class='hs-comment'>----------- Wrappers for algebraic data types -------------- </span>
<a name="line-85"></a> <span class='hs-varid'>alg_wrap_id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>DataConWrapId</span> <span class='hs-varid'>data_con</span><span class='hs-layout'>)</span> <span class='hs-varid'>wrap_name</span> <span class='hs-varid'>wrap_ty</span> <span class='hs-varid'>alg_wrap_info</span>
<a name="line-86"></a> <span class='hs-varid'>alg_wrap_info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span> <span class='hs-comment'>-- The NoCaf-ness is set by noCafIdInfo</span>
<a name="line-87"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-varid'>wrap_arity</span>
<a name="line-88"></a> <span class='hs-comment'>-- It's important to specify the arity, so that partial</span>
<a name="line-89"></a> <span class='hs-comment'>-- applications are treated as values</span>
<a name="line-90"></a> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>wrap_unf</span>
<a name="line-91"></a> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>wrap_sig</span>
<a name="line-92"></a>
<a name="line-93"></a> <span class='hs-varid'>all_strict_marks</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConExStricts</span> <span class='hs-varid'>data_con</span> <span class='hs-varop'>++</span> <span class='hs-varid'>dataConStrictMarks</span> <span class='hs-varid'>data_con</span>
<a name="line-94"></a> <span class='hs-varid'>wrap_sig</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkStrictSig</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopDmdType</span> <span class='hs-varid'>arg_dmds</span> <span class='hs-varid'>cpr_info</span><span class='hs-layout'>)</span>
<a name="line-95"></a> <span class='hs-varid'>arg_dmds</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>mk_dmd</span> <span class='hs-varid'>all_strict_marks</span>
<a name="line-96"></a> <span class='hs-varid'>mk_dmd</span> <span class='hs-varid'>str</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isMarkedStrict</span> <span class='hs-varid'>str</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>evalDmd</span>
<a name="line-97"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lazyDmd</span>
<a name="line-98"></a> <span class='hs-comment'>-- The Cpr info can be important inside INLINE rhss, where the</span>
<a name="line-99"></a> <span class='hs-comment'>-- wrapper constructor isn't inlined.</span>
<a name="line-100"></a> <span class='hs-comment'>-- And the argument strictness can be important too; we</span>
<a name="line-101"></a> <span class='hs-comment'>-- may not inline a contructor when it is partially applied.</span>
<a name="line-102"></a> <span class='hs-comment'>-- For example:</span>
<a name="line-103"></a> <span class='hs-comment'>-- data W = C !Int !Int !Int</span>
<a name="line-104"></a> <span class='hs-comment'>-- ...(let w = C x in ...(w p q)...)...</span>
<a name="line-105"></a> <span class='hs-comment'>-- we want to see that w is strict in its two arguments</span>
<a name="line-106"></a>
<a name="line-107"></a> <span class='hs-varid'>wrap_unf</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkImplicitUnfolding</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Note</span> <span class='hs-conid'>InlineMe</span> <span class='hs-varop'>$</span>
<a name="line-108"></a> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>wrap_tvs</span> <span class='hs-varop'>$</span>
<a name="line-109"></a> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>eq_args</span> <span class='hs-varop'>$</span>
<a name="line-110"></a> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>dict_args</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>id_args</span> <span class='hs-varop'>$</span>
<a name="line-111"></a> <span class='hs-varid'>foldr</span> <span class='hs-varid'>mk_case</span> <span class='hs-varid'>con_app</span>
<a name="line-112"></a> <span class='hs-layout'>(</span><span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>dict_args</span> <span class='hs-varop'>++</span> <span class='hs-varid'>id_args</span><span class='hs-layout'>)</span> <span class='hs-varid'>all_strict_marks</span><span class='hs-layout'>)</span>
<a name="line-113"></a> <span class='hs-varid'>i3</span> <span class='hs-conid'>[]</span>
<a name="line-114"></a>
<a name="line-115"></a> <span class='hs-varid'>con_app</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>rep_ids</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>wrapFamInstBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>res_ty_args</span> <span class='hs-varop'>$</span>
<a name="line-116"></a> <span class='hs-conid'>Var</span> <span class='hs-varid'>wrk_id</span> <span class='hs-varop'>`mkTyApps`</span> <span class='hs-varid'>res_ty_args</span>
<a name="line-117"></a> <span class='hs-varop'>`mkVarApps`</span> <span class='hs-varid'>ex_tvs</span>
<a name="line-118"></a> <span class='hs-comment'>-- Equality evidence:</span>
<a name="line-119"></a> <span class='hs-varop'>`mkTyApps`</span> <span class='hs-varid'>map</span> <span class='hs-varid'>snd</span> <span class='hs-varid'>eq_spec</span>
<a name="line-120"></a> <span class='hs-varop'>`mkVarApps`</span> <span class='hs-varid'>eq_args</span>
<a name="line-121"></a> <span class='hs-varop'>`mkVarApps`</span> <span class='hs-varid'>reverse</span> <span class='hs-varid'>rep_ids</span>
<a name="line-122"></a>
<a name="line-123"></a> <span class='hs-layout'>(</span><span class='hs-varid'>dict_args</span><span class='hs-layout'>,</span><span class='hs-varid'>i2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLocals</span> <span class='hs-num'>1</span> <span class='hs-varid'>dict_tys</span>
<a name="line-124"></a> <span class='hs-layout'>(</span><span class='hs-varid'>id_args</span><span class='hs-layout'>,</span><span class='hs-varid'>i3</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLocals</span> <span class='hs-varid'>i2</span> <span class='hs-varid'>orig_arg_tys</span>
<a name="line-125"></a> <span class='hs-varid'>wrap_arity</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>i3</span><span class='hs-comment'>-</span><span class='hs-num'>1</span>
<a name="line-126"></a> <span class='hs-layout'>(</span><span class='hs-varid'>eq_args</span><span class='hs-layout'>,</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-varid'>i3</span> <span class='hs-varid'>eq_tys</span>
<a name="line-127"></a>
<a name="line-128"></a> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-varid'>i</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span><span class='hs-varid'>i</span><span class='hs-layout'>)</span>
<a name="line-129"></a> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>ys</span><span class='hs-layout'>,</span><span class='hs-varid'>j</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-130"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVar</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkSysTvName</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkBuiltinUnique</span> <span class='hs-varid'>i</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"dc_co"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span>
<a name="line-131"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span><span class='hs-conop'>:</span><span class='hs-varid'>ys</span><span class='hs-layout'>,</span><span class='hs-varid'>j</span><span class='hs-layout'>)</span>
<a name="line-132"></a>
<a name="line-133"></a> <span class='hs-varid'>mk_case</span>
<a name="line-134"></a> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Id</span><span class='hs-layout'>,</span> <span class='hs-conid'>StrictnessMark</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- Arg, strictness</span>
<a name="line-135"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- Body</span>
<a name="line-136"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- Next rep arg id</span>
<a name="line-137"></a> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- Rep args so far, reversed</span>
<a name="line-138"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-139"></a> <span class='hs-varid'>mk_case</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-layout'>,</span><span class='hs-varid'>strict</span><span class='hs-layout'>)</span> <span class='hs-varid'>body</span> <span class='hs-varid'>i</span> <span class='hs-varid'>rep_args</span>
<a name="line-140"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>strict</span> <span class='hs-keyword'>of</span>
<a name="line-141"></a> <span class='hs-conid'>NotMarkedStrict</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>body</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>rep_args</span><span class='hs-layout'>)</span>
<a name="line-142"></a> <span class='hs-conid'>MarkedStrict</span>
<a name="line-143"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isUnLiftedType</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>body</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>rep_args</span><span class='hs-layout'>)</span>
<a name="line-144"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>-></span>
<a name="line-145"></a> <span class='hs-conid'>Case</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span> <span class='hs-varid'>arg</span> <span class='hs-varid'>res_ty</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>DEFAULT</span><span class='hs-layout'>,</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-varid'>body</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>rep_args</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-146"></a>
<a name="line-147"></a> <span class='hs-conid'>MarkedUnboxed</span>
<a name="line-148"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>unboxProduct</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span> <span class='hs-varid'>the_body</span>
<a name="line-149"></a> <span class='hs-keyword'>where</span>
<a name="line-150"></a> <span class='hs-varid'>the_body</span> <span class='hs-varid'>i</span> <span class='hs-varid'>con_args</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>body</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>con_args</span> <span class='hs-varop'>++</span> <span class='hs-varid'>rep_args</span><span class='hs-layout'>)</span>
<a name="line-151"></a>
<a name="line-152"></a><a name="mAX_CPR_SIZE"></a><span class='hs-definition'>mAX_CPR_SIZE</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Arity</span>
<a name="line-153"></a><span class='hs-definition'>mAX_CPR_SIZE</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>10</span>
<a name="line-154"></a><span class='hs-comment'>-- We do not treat very big tuples as CPR-ish:</span>
<a name="line-155"></a><span class='hs-comment'>-- a) for a start we get into trouble because there aren't </span>
<a name="line-156"></a><span class='hs-comment'>-- "enough" unboxed tuple types (a tiresome restriction, </span>
<a name="line-157"></a><span class='hs-comment'>-- but hard to fix), </span>
<a name="line-158"></a><span class='hs-comment'>-- b) more importantly, big unboxed tuples get returned mainly</span>
<a name="line-159"></a><span class='hs-comment'>-- on the stack, and are often then allocated in the heap</span>
<a name="line-160"></a><span class='hs-comment'>-- by the caller. So doing CPR for them may in fact make</span>
<a name="line-161"></a><span class='hs-comment'>-- things worse.</span>
<a name="line-162"></a>
<a name="line-163"></a><a name="mkLocals"></a><span class='hs-definition'>mkLocals</span> <span class='hs-varid'>i</span> <span class='hs-varid'>tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>zipWith</span> <span class='hs-varid'>mkTemplateLocal</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>i</span><span class='hs-keyglyph'>..</span><span class='hs-varid'>i</span><span class='hs-varop'>+</span><span class='hs-varid'>n</span><span class='hs-comment'>-</span><span class='hs-num'>1</span><span class='hs-keyglyph'>]</span> <span class='hs-varid'>tys</span><span class='hs-layout'>,</span> <span class='hs-varid'>i</span><span class='hs-varop'>+</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-164"></a> <span class='hs-keyword'>where</span>
<a name="line-165"></a> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>length</span> <span class='hs-varid'>tys</span>
</pre>\end{code}
Note [Newtype datacons]
~~~~~~~~~~~~~~~~~~~~~~~
The "data constructor" for a newtype should always be vanilla. At one
point this wasn't true, because the newtype arising from
class C a => D a
looked like
newtype T:D a = D:D (C a)
so the data constructor for T:C had a single argument, namely the
predicate (C a). But now we treat that as an ordinary argument, not
part of the theta-type, so all is well.
%************************************************************************
%* *
\subsection{Dictionary selectors}
%* *
%************************************************************************
Selecting a field for a dictionary. If there is just one field, then
there's nothing to do.
Dictionary selectors may get nested forall-types. Thus:
class Foo a where
op :: forall b. Ord b => a -> b -> b
Then the top-level type for op is
op :: forall a. Foo a =>
forall b. Ord b =>
a -> b -> b
This is unlike ordinary record selectors, which have all the for-alls
at the outside. When dealing with classes it's very convenient to
recover the original type signature from the class op selector.
\begin{code}
<pre><a name="line-1"></a><a name="mkDictSelId"></a><span class='hs-definition'>mkDictSelId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bool</span> <span class='hs-comment'>-- True <=> don't include the unfolding</span>
<a name="line-2"></a> <span class='hs-comment'>-- Little point on imports without -O, because the</span>
<a name="line-3"></a> <span class='hs-comment'>-- dictionary itself won't be visible</span>
<a name="line-4"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Class</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-5"></a><span class='hs-definition'>mkDictSelId</span> <span class='hs-varid'>no_unf</span> <span class='hs-varid'>name</span> <span class='hs-varid'>clas</span>
<a name="line-6"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>ClassOpId</span> <span class='hs-varid'>clas</span><span class='hs-layout'>)</span> <span class='hs-varid'>name</span> <span class='hs-varid'>sel_ty</span> <span class='hs-varid'>info</span>
<a name="line-7"></a> <span class='hs-keyword'>where</span>
<a name="line-8"></a> <span class='hs-varid'>sel_ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-varid'>tyvars</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>dict_id</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>the_arg_id</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-9"></a> <span class='hs-comment'>-- We can't just say (exprType rhs), because that would give a type</span>
<a name="line-10"></a> <span class='hs-comment'>-- C a -> C a</span>
<a name="line-11"></a> <span class='hs-comment'>-- for a single-op class (after all, the selector is the identity)</span>
<a name="line-12"></a> <span class='hs-comment'>-- But it's type must expose the representation of the dictionary</span>
<a name="line-13"></a> <span class='hs-comment'>-- to get (say) C a -> (a -> a)</span>
<a name="line-14"></a>
<a name="line-15"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
<a name="line-16"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-num'>1</span>
<a name="line-17"></a> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>strict_sig</span>
<a name="line-18"></a> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-layout'>(</span><span class='hs-keyword'>if</span> <span class='hs-varid'>no_unf</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>noUnfolding</span>
<a name="line-19"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>mkImplicitUnfolding</span> <span class='hs-varid'>rhs</span><span class='hs-layout'>)</span>
<a name="line-20"></a>
<a name="line-21"></a> <span class='hs-comment'>-- We no longer use 'must-inline' on record selectors. They'll</span>
<a name="line-22"></a> <span class='hs-comment'>-- inline like crazy if they scrutinise a constructor</span>
<a name="line-23"></a>
<a name="line-24"></a> <span class='hs-comment'>-- The strictness signature is of the form U(AAAVAAAA) -> T</span>
<a name="line-25"></a> <span class='hs-comment'>-- where the V depends on which item we are selecting</span>
<a name="line-26"></a> <span class='hs-comment'>-- It's worth giving one, so that absence info etc is generated</span>
<a name="line-27"></a> <span class='hs-comment'>-- even if the selector isn't inlined</span>
<a name="line-28"></a> <span class='hs-varid'>strict_sig</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkStrictSig</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopDmdType</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>arg_dmd</span><span class='hs-keyglyph'>]</span> <span class='hs-conid'>TopRes</span><span class='hs-layout'>)</span>
<a name="line-29"></a> <span class='hs-varid'>arg_dmd</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>evalDmd</span>
<a name="line-30"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Eval</span> <span class='hs-layout'>(</span><span class='hs-conid'>Prod</span> <span class='hs-keyglyph'>[</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>the_arg_id</span> <span class='hs-varop'>==</span> <span class='hs-varid'>id</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>evalDmd</span> <span class='hs-keyword'>else</span> <span class='hs-conid'>Abs</span>
<a name="line-31"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>id</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>arg_ids</span> <span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-32"></a>
<a name="line-33"></a> <span class='hs-varid'>tycon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>classTyCon</span> <span class='hs-varid'>clas</span>
<a name="line-34"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>data_con</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tyConDataCons</span> <span class='hs-varid'>tycon</span>
<a name="line-35"></a> <span class='hs-varid'>tyvars</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConUnivTyVars</span> <span class='hs-varid'>data_con</span>
<a name="line-36"></a> <span class='hs-varid'>arg_tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-comment'>{- ASSERT( isVanillaDataCon data_con ) -}</span> <span class='hs-varid'>dataConRepArgTys</span> <span class='hs-varid'>data_con</span>
<a name="line-37"></a> <span class='hs-varid'>eq_theta</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConEqTheta</span> <span class='hs-varid'>data_con</span>
<a name="line-38"></a> <span class='hs-varid'>the_arg_id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>assoc</span> <span class='hs-str'>"MkId.mkDictSelId"</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>idName</span> <span class='hs-layout'>(</span><span class='hs-varid'>classSelIds</span> <span class='hs-varid'>clas</span><span class='hs-layout'>)</span> <span class='hs-varop'>`zip`</span> <span class='hs-varid'>arg_ids</span><span class='hs-layout'>)</span> <span class='hs-varid'>name</span>
<a name="line-39"></a>
<a name="line-40"></a> <span class='hs-varid'>pred</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkClassPred</span> <span class='hs-varid'>clas</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyVarTys</span> <span class='hs-varid'>tyvars</span><span class='hs-layout'>)</span>
<a name="line-41"></a> <span class='hs-varid'>dict_id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTemplateLocal</span> <span class='hs-num'>1</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mkPredTy</span> <span class='hs-varid'>pred</span>
<a name="line-42"></a> <span class='hs-layout'>(</span><span class='hs-varid'>eq_ids</span><span class='hs-layout'>,</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-num'>2</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mkPredTys</span> <span class='hs-varid'>eq_theta</span>
<a name="line-43"></a> <span class='hs-varid'>arg_ids</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTemplateLocalsNum</span> <span class='hs-varid'>n</span> <span class='hs-varid'>arg_tys</span>
<a name="line-44"></a>
<a name="line-45"></a> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-varid'>i</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span><span class='hs-varid'>i</span><span class='hs-layout'>)</span>
<a name="line-46"></a> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-varid'>i</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>ys</span><span class='hs-layout'>,</span><span class='hs-varid'>j</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVarLocals</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-47"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoVar</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkSysTvName</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkBuiltinUnique</span> <span class='hs-varid'>i</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"dc_co"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span>
<a name="line-48"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span><span class='hs-conop'>:</span><span class='hs-varid'>ys</span><span class='hs-layout'>,</span><span class='hs-varid'>j</span><span class='hs-layout'>)</span>
<a name="line-49"></a>
<a name="line-50"></a> <span class='hs-varid'>rhs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLams</span> <span class='hs-varid'>tyvars</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lam</span> <span class='hs-varid'>dict_id</span> <span class='hs-varid'>rhs_body</span><span class='hs-layout'>)</span>
<a name="line-51"></a> <span class='hs-varid'>rhs_body</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unwrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>mkTyVarTy</span> <span class='hs-varid'>tyvars</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>dict_id</span><span class='hs-layout'>)</span>
<a name="line-52"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Case</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>dict_id</span><span class='hs-layout'>)</span> <span class='hs-varid'>dict_id</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>the_arg_id</span><span class='hs-layout'>)</span>
<a name="line-53"></a> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>DataAlt</span> <span class='hs-varid'>data_con</span><span class='hs-layout'>,</span> <span class='hs-varid'>eq_ids</span> <span class='hs-varop'>++</span> <span class='hs-varid'>arg_ids</span><span class='hs-layout'>,</span> <span class='hs-conid'>Var</span> <span class='hs-varid'>the_arg_id</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
</pre>\end{code}
%************************************************************************
%* *
Boxing and unboxing
%* *
%************************************************************************
\begin{code}
<pre><a name="line-1"></a><a name="unboxProduct"></a><span class='hs-comment'>-- unbox a product type...</span>
<a name="line-2"></a><span class='hs-comment'>-- we will recurse into newtypes, casting along the way, and unbox at the</span>
<a name="line-3"></a><span class='hs-comment'>-- first product data constructor we find. e.g.</span>
<a name="line-4"></a><span class='hs-comment'>-- </span>
<a name="line-5"></a><span class='hs-comment'>-- data PairInt = PairInt Int Int</span>
<a name="line-6"></a><span class='hs-comment'>-- newtype S = MkS PairInt</span>
<a name="line-7"></a><span class='hs-comment'>-- newtype T = MkT S</span>
<a name="line-8"></a><span class='hs-comment'>--</span>
<a name="line-9"></a><span class='hs-comment'>-- If we have e = MkT (MkS (PairInt 0 1)) and some body expecting a list of</span>
<a name="line-10"></a><span class='hs-comment'>-- ids, we get (modulo int passing)</span>
<a name="line-11"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><span class='hs-comment'>-- case (e `cast` CoT) `cast` CoS of</span>
<a name="line-13"></a><span class='hs-comment'>-- PairInt a b -> body [a,b]</span>
<a name="line-14"></a><span class='hs-comment'>--</span>
<a name="line-15"></a><span class='hs-comment'>-- The Ints passed around are just for creating fresh locals</span>
<a name="line-16"></a><span class='hs-definition'>unboxProduct</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-17"></a><span class='hs-definition'>unboxProduct</span> <span class='hs-varid'>i</span> <span class='hs-varid'>arg</span> <span class='hs-varid'>arg_ty</span> <span class='hs-varid'>body</span>
<a name="line-18"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>result</span>
<a name="line-19"></a> <span class='hs-keyword'>where</span>
<a name="line-20"></a> <span class='hs-varid'>result</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkUnpackCase</span> <span class='hs-varid'>the_id</span> <span class='hs-varid'>arg</span> <span class='hs-varid'>con_args</span> <span class='hs-varid'>boxing_con</span> <span class='hs-varid'>rhs</span>
<a name="line-21"></a> <span class='hs-layout'>(</span><span class='hs-sel'>_tycon</span><span class='hs-layout'>,</span> <span class='hs-sel'>_tycon_args</span><span class='hs-layout'>,</span> <span class='hs-varid'>boxing_con</span><span class='hs-layout'>,</span> <span class='hs-varid'>tys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>deepSplitProductType</span> <span class='hs-str'>"unboxProduct"</span> <span class='hs-varid'>arg_ty</span>
<a name="line-22"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>[</span><span class='hs-varid'>the_id</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>,</span> <span class='hs-varid'>i'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLocals</span> <span class='hs-varid'>i</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>arg_ty</span><span class='hs-keyglyph'>]</span>
<a name="line-23"></a> <span class='hs-layout'>(</span><span class='hs-varid'>con_args</span><span class='hs-layout'>,</span> <span class='hs-varid'>i''</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLocals</span> <span class='hs-varid'>i'</span> <span class='hs-varid'>tys</span>
<a name="line-24"></a> <span class='hs-varid'>rhs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>body</span> <span class='hs-varid'>i''</span> <span class='hs-varid'>con_args</span>
<a name="line-25"></a>
<a name="line-26"></a><a name="mkUnpackCase"></a><span class='hs-definition'>mkUnpackCase</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DataCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-27"></a><span class='hs-comment'>-- (mkUnpackCase x e args Con body)</span>
<a name="line-28"></a><span class='hs-comment'>-- returns</span>
<a name="line-29"></a><span class='hs-comment'>-- case (e `cast` ...) of bndr { Con args -> body }</span>
<a name="line-30"></a><span class='hs-comment'>-- </span>
<a name="line-31"></a><span class='hs-comment'>-- the type of the bndr passed in is irrelevent</span>
<a name="line-32"></a><span class='hs-definition'>mkUnpackCase</span> <span class='hs-varid'>bndr</span> <span class='hs-varid'>arg</span> <span class='hs-varid'>unpk_args</span> <span class='hs-varid'>boxing_con</span> <span class='hs-varid'>body</span>
<a name="line-33"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Case</span> <span class='hs-varid'>cast_arg</span> <span class='hs-layout'>(</span><span class='hs-varid'>setIdType</span> <span class='hs-varid'>bndr</span> <span class='hs-varid'>bndr_ty</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>exprType</span> <span class='hs-varid'>body</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>DataAlt</span> <span class='hs-varid'>boxing_con</span><span class='hs-layout'>,</span> <span class='hs-varid'>unpk_args</span><span class='hs-layout'>,</span> <span class='hs-varid'>body</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-34"></a> <span class='hs-keyword'>where</span>
<a name="line-35"></a> <span class='hs-layout'>(</span><span class='hs-varid'>cast_arg</span><span class='hs-layout'>,</span> <span class='hs-varid'>bndr_ty</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>bndr</span><span class='hs-layout'>)</span> <span class='hs-varid'>arg</span>
<a name="line-36"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>arg</span>
<a name="line-37"></a> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-varid'>tycon</span><span class='hs-layout'>,</span> <span class='hs-varid'>tycon_args</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>splitProductType</span> <span class='hs-str'>"mkUnpackCase"</span> <span class='hs-varid'>ty</span>
<a name="line-38"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>isRecursiveTyCon</span> <span class='hs-varid'>tycon</span><span class='hs-layout'>)</span>
<a name="line-39"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>newTyConInstRhs</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>tycon_args</span><span class='hs-layout'>)</span>
<a name="line-40"></a> <span class='hs-layout'>(</span><span class='hs-varid'>unwrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>tycon_args</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span>
<a name="line-41"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-layout'>,</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-42"></a>
<a name="line-43"></a><a name="reboxProduct"></a><span class='hs-comment'>-- ...and the dual</span>
<a name="line-44"></a><span class='hs-definition'>reboxProduct</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Unique</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- uniques to create new local binders</span>
<a name="line-45"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- type of product to box</span>
<a name="line-46"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>[</span><span class='hs-conid'>Unique</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- remaining uniques</span>
<a name="line-47"></a> <span class='hs-conid'>CoreExpr</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- boxed product</span>
<a name="line-48"></a> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- Ids being boxed into product</span>
<a name="line-49"></a><span class='hs-definition'>reboxProduct</span> <span class='hs-varid'>us</span> <span class='hs-varid'>ty</span>
<a name="line-50"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span>
<a name="line-51"></a> <span class='hs-layout'>(</span><span class='hs-sel'>_tycon</span><span class='hs-layout'>,</span> <span class='hs-sel'>_tycon_args</span><span class='hs-layout'>,</span> <span class='hs-sel'>_pack_con</span><span class='hs-layout'>,</span> <span class='hs-varid'>con_arg_tys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>deepSplitProductType</span> <span class='hs-str'>"reboxProduct"</span> <span class='hs-varid'>ty</span>
<a name="line-52"></a>
<a name="line-53"></a> <span class='hs-varid'>us'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dropList</span> <span class='hs-varid'>con_arg_tys</span> <span class='hs-varid'>us</span>
<a name="line-54"></a>
<a name="line-55"></a> <span class='hs-varid'>arg_ids</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zipWith</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkSysLocal</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"rb"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>us</span> <span class='hs-varid'>con_arg_tys</span>
<a name="line-56"></a>
<a name="line-57"></a> <span class='hs-varid'>bind_rhs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkProductBox</span> <span class='hs-varid'>arg_ids</span> <span class='hs-varid'>ty</span>
<a name="line-58"></a>
<a name="line-59"></a> <span class='hs-keyword'>in</span>
<a name="line-60"></a> <span class='hs-layout'>(</span><span class='hs-varid'>us'</span><span class='hs-layout'>,</span> <span class='hs-varid'>bind_rhs</span><span class='hs-layout'>,</span> <span class='hs-varid'>arg_ids</span><span class='hs-layout'>)</span>
<a name="line-61"></a>
<a name="line-62"></a><a name="mkProductBox"></a><span class='hs-definition'>mkProductBox</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Id</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-63"></a><span class='hs-definition'>mkProductBox</span> <span class='hs-varid'>arg_ids</span> <span class='hs-varid'>ty</span>
<a name="line-64"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>result_expr</span>
<a name="line-65"></a> <span class='hs-keyword'>where</span>
<a name="line-66"></a> <span class='hs-layout'>(</span><span class='hs-varid'>tycon</span><span class='hs-layout'>,</span> <span class='hs-varid'>tycon_args</span><span class='hs-layout'>,</span> <span class='hs-varid'>pack_con</span><span class='hs-layout'>,</span> <span class='hs-sel'>_con_arg_tys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitProductType</span> <span class='hs-str'>"mkProductBox"</span> <span class='hs-varid'>ty</span>
<a name="line-67"></a>
<a name="line-68"></a> <span class='hs-varid'>result_expr</span>
<a name="line-69"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tycon</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>isRecursiveTyCon</span> <span class='hs-varid'>tycon</span><span class='hs-layout'>)</span>
<a name="line-70"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>wrap</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkProductBox</span> <span class='hs-varid'>arg_ids</span> <span class='hs-layout'>(</span><span class='hs-varid'>newTyConInstRhs</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>tycon_args</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-71"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkConApp</span> <span class='hs-varid'>pack_con</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-conid'>Type</span> <span class='hs-varid'>tycon_args</span> <span class='hs-varop'>++</span> <span class='hs-varid'>map</span> <span class='hs-conid'>Var</span> <span class='hs-varid'>arg_ids</span><span class='hs-layout'>)</span>
<a name="line-72"></a>
<a name="line-73"></a> <span class='hs-varid'>wrap</span> <span class='hs-varid'>expr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>wrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>tycon_args</span> <span class='hs-varid'>expr</span>
<a name="line-74"></a>
<a name="line-75"></a>
<a name="line-76"></a><span class='hs-comment'>-- (mkReboxingAlt us con xs rhs) basically constructs the case</span>
<a name="line-77"></a><span class='hs-comment'>-- alternative (con, xs, rhs)</span>
<a name="line-78"></a><span class='hs-comment'>-- but it does the reboxing necessary to construct the *source* </span>
<a name="line-79"></a><span class='hs-comment'>-- arguments, xs, from the representation arguments ys.</span>
<a name="line-80"></a><span class='hs-comment'>-- For example:</span>
<a name="line-81"></a><span class='hs-comment'>-- data T = MkT !(Int,Int) Bool</span>
<a name="line-82"></a><span class='hs-comment'>--</span>
<a name="line-83"></a><span class='hs-comment'>-- mkReboxingAlt MkT [x,b] r </span>
<a name="line-84"></a><span class='hs-comment'>-- = (DataAlt MkT, [y::Int,z::Int,b], let x = (y,z) in r)</span>
<a name="line-85"></a><span class='hs-comment'>--</span>
<a name="line-86"></a><span class='hs-comment'>-- mkDataAlt should really be in DataCon, but it can't because</span>
<a name="line-87"></a><span class='hs-comment'>-- it manipulates CoreSyn.</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="mkReboxingAlt"></a><span class='hs-definition'>mkReboxingAlt</span>
<a name="line-90"></a> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Unique</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- Uniques for the new Ids</span>
<a name="line-91"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DataCon</span>
<a name="line-92"></a> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Var</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- Source-level args, including existential dicts</span>
<a name="line-93"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-comment'>-- RHS</span>
<a name="line-94"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreAlt</span>
<a name="line-95"></a>
<a name="line-96"></a><span class='hs-definition'>mkReboxingAlt</span> <span class='hs-varid'>us</span> <span class='hs-varid'>con</span> <span class='hs-varid'>args</span> <span class='hs-varid'>rhs</span>
<a name="line-97"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>any</span> <span class='hs-varid'>isMarkedUnboxed</span> <span class='hs-varid'>stricts</span><span class='hs-layout'>)</span>
<a name="line-98"></a> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>DataAlt</span> <span class='hs-varid'>con</span><span class='hs-layout'>,</span> <span class='hs-varid'>args</span><span class='hs-layout'>,</span> <span class='hs-varid'>rhs</span><span class='hs-layout'>)</span>
<a name="line-99"></a>
<a name="line-100"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-101"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span>
<a name="line-102"></a> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>args'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-varid'>args</span> <span class='hs-varid'>stricts</span> <span class='hs-varid'>us</span>
<a name="line-103"></a> <span class='hs-keyword'>in</span>
<a name="line-104"></a> <span class='hs-layout'>(</span><span class='hs-conid'>DataAlt</span> <span class='hs-varid'>con</span><span class='hs-layout'>,</span> <span class='hs-varid'>args'</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkLets</span> <span class='hs-varid'>binds</span> <span class='hs-varid'>rhs</span><span class='hs-layout'>)</span>
<a name="line-105"></a>
<a name="line-106"></a> <span class='hs-keyword'>where</span>
<a name="line-107"></a> <span class='hs-varid'>stricts</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConExStricts</span> <span class='hs-varid'>con</span> <span class='hs-varop'>++</span> <span class='hs-varid'>dataConStrictMarks</span> <span class='hs-varid'>con</span>
<a name="line-108"></a>
<a name="line-109"></a> <span class='hs-varid'>go</span> <span class='hs-conid'>[]</span> <span class='hs-sel'>_stricts</span> <span class='hs-sel'>_us</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span>
<a name="line-110"></a>
<a name="line-111"></a> <span class='hs-comment'>-- Type variable case</span>
<a name="line-112"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>args</span><span class='hs-layout'>)</span> <span class='hs-varid'>stricts</span> <span class='hs-varid'>us</span>
<a name="line-113"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isTyVar</span> <span class='hs-varid'>arg</span>
<a name="line-114"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>args'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-varid'>args</span> <span class='hs-varid'>stricts</span> <span class='hs-varid'>us</span>
<a name="line-115"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>args'</span><span class='hs-layout'>)</span>
<a name="line-116"></a>
<a name="line-117"></a> <span class='hs-comment'>-- Term variable case</span>
<a name="line-118"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>args</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>str</span><span class='hs-conop'>:</span><span class='hs-varid'>stricts</span><span class='hs-layout'>)</span> <span class='hs-varid'>us</span>
<a name="line-119"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isMarkedUnboxed</span> <span class='hs-varid'>str</span>
<a name="line-120"></a> <span class='hs-keyglyph'>=</span>
<a name="line-121"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>unpacked_args'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-varid'>args</span> <span class='hs-varid'>stricts</span> <span class='hs-varid'>us'</span>
<a name="line-122"></a> <span class='hs-layout'>(</span><span class='hs-varid'>us'</span><span class='hs-layout'>,</span> <span class='hs-varid'>bind_rhs</span><span class='hs-layout'>,</span> <span class='hs-varid'>unpacked_args</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reboxProduct</span> <span class='hs-varid'>us</span> <span class='hs-layout'>(</span><span class='hs-varid'>idType</span> <span class='hs-varid'>arg</span><span class='hs-layout'>)</span>
<a name="line-123"></a> <span class='hs-keyword'>in</span>
<a name="line-124"></a> <span class='hs-layout'>(</span><span class='hs-conid'>NonRec</span> <span class='hs-varid'>arg</span> <span class='hs-varid'>bind_rhs</span> <span class='hs-conop'>:</span> <span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>unpacked_args</span> <span class='hs-varop'>++</span> <span class='hs-varid'>unpacked_args'</span><span class='hs-layout'>)</span>
<a name="line-125"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-126"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>args'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-varid'>args</span> <span class='hs-varid'>stricts</span> <span class='hs-varid'>us</span>
<a name="line-127"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>binds</span><span class='hs-layout'>,</span> <span class='hs-varid'>arg</span><span class='hs-conop'>:</span><span class='hs-varid'>args'</span><span class='hs-layout'>)</span>
<a name="line-128"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span> <span class='hs-conop'>:</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-conid'>[]</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>panic</span> <span class='hs-str'>"mkReboxingAlt"</span>
</pre>\end{code}
%************************************************************************
%* *
Wrapping and unwrapping newtypes and type families
%* *
%************************************************************************
\begin{code}
<pre><a name="line-1"></a><a name="wrapNewTypeBody"></a><span class='hs-definition'>wrapNewTypeBody</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-2"></a><span class='hs-comment'>-- The wrapper for the data constructor for a newtype looks like this:</span>
<a name="line-3"></a><span class='hs-comment'>-- newtype T a = MkT (a,Int)</span>
<a name="line-4"></a><span class='hs-comment'>-- MkT :: forall a. (a,Int) -> T a</span>
<a name="line-5"></a><span class='hs-comment'>-- MkT = /\a. \(x:(a,Int)). x `cast` sym (CoT a)</span>
<a name="line-6"></a><span class='hs-comment'>-- where CoT is the coercion TyCon assoicated with the newtype</span>
<a name="line-7"></a><span class='hs-comment'>--</span>
<a name="line-8"></a><span class='hs-comment'>-- The call (wrapNewTypeBody T [a] e) returns the</span>
<a name="line-9"></a><span class='hs-comment'>-- body of the wrapper, namely</span>
<a name="line-10"></a><span class='hs-comment'>-- e `cast` (CoT [a])</span>
<a name="line-11"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><span class='hs-comment'>-- If a coercion constructor is provided in the newtype, then we use</span>
<a name="line-13"></a><span class='hs-comment'>-- it, otherwise the wrap/unwrap are both no-ops </span>
<a name="line-14"></a><span class='hs-comment'>--</span>
<a name="line-15"></a><span class='hs-comment'>-- If the we are dealing with a newtype *instance*, we have a second coercion</span>
<a name="line-16"></a><span class='hs-comment'>-- identifying the family instance with the constructor of the newtype</span>
<a name="line-17"></a><span class='hs-comment'>-- instance. This coercion is applied in any case (ie, composed with the</span>
<a name="line-18"></a><span class='hs-comment'>-- coercion constructor of the newtype or applied by itself).</span>
<a name="line-19"></a>
<a name="line-20"></a><span class='hs-definition'>wrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>args</span> <span class='hs-varid'>result_expr</span>
<a name="line-21"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>wrapFamInstBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>args</span> <span class='hs-varid'>inner</span>
<a name="line-22"></a> <span class='hs-keyword'>where</span>
<a name="line-23"></a> <span class='hs-varid'>inner</span>
<a name="line-24"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>co_con</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newTyConCo_maybe</span> <span class='hs-varid'>tycon</span>
<a name="line-25"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoerce</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkSymCoercion</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>co_con</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>result_expr</span>
<a name="line-26"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-27"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>result_expr</span>
<a name="line-28"></a>
<a name="line-29"></a><span class='hs-comment'>-- When unwrapping, we do *not* apply any family coercion, because this will</span>
<a name="line-30"></a><span class='hs-comment'>-- be done via a CoPat by the type checker. We have to do it this way as</span>
<a name="line-31"></a><span class='hs-comment'>-- computing the right type arguments for the coercion requires more than just</span>
<a name="line-32"></a><span class='hs-comment'>-- a spliting operation (cf, TcPat.tcConPat).</span>
<a name="line-33"></a>
<a name="line-34"></a><a name="unwrapNewTypeBody"></a><span class='hs-definition'>unwrapNewTypeBody</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-35"></a><span class='hs-definition'>unwrapNewTypeBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>args</span> <span class='hs-varid'>result_expr</span>
<a name="line-36"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>co_con</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newTyConCo_maybe</span> <span class='hs-varid'>tycon</span>
<a name="line-37"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoerce</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>co_con</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span> <span class='hs-varid'>result_expr</span>
<a name="line-38"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-39"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>result_expr</span>
<a name="line-40"></a>
<a name="line-41"></a><a name="wrapFamInstBody"></a><span class='hs-comment'>-- If the type constructor is a representation type of a data instance, wrap</span>
<a name="line-42"></a><span class='hs-comment'>-- the expression into a cast adjusting the expression type, which is an</span>
<a name="line-43"></a><span class='hs-comment'>-- instance of the representation type, to the corresponding instance of the</span>
<a name="line-44"></a><span class='hs-comment'>-- family instance type.</span>
<a name="line-45"></a><span class='hs-comment'>-- See Note [Wrappers for data instance tycons]</span>
<a name="line-46"></a><span class='hs-definition'>wrapFamInstBody</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-47"></a><span class='hs-definition'>wrapFamInstBody</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>args</span> <span class='hs-varid'>body</span>
<a name="line-48"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>co_con</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>tyConFamilyCoercion_maybe</span> <span class='hs-varid'>tycon</span>
<a name="line-49"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoerce</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkSymCoercion</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>co_con</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>body</span>
<a name="line-50"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-51"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>body</span>
<a name="line-52"></a>
<a name="line-53"></a><a name="unwrapFamInstScrut"></a><span class='hs-definition'>unwrapFamInstScrut</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-54"></a><span class='hs-definition'>unwrapFamInstScrut</span> <span class='hs-varid'>tycon</span> <span class='hs-varid'>args</span> <span class='hs-varid'>scrut</span>
<a name="line-55"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>co_con</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>tyConFamilyCoercion_maybe</span> <span class='hs-varid'>tycon</span>
<a name="line-56"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkCoerce</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>co_con</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span> <span class='hs-varid'>scrut</span>
<a name="line-57"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-58"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>scrut</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{Primitive operations}
%* *
%************************************************************************
\begin{code}
<pre><a name="line-1"></a><a name="mkPrimOpId"></a><span class='hs-definition'>mkPrimOpId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>PrimOp</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-2"></a><span class='hs-definition'>mkPrimOpId</span> <span class='hs-varid'>prim_op</span>
<a name="line-3"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-4"></a> <span class='hs-keyword'>where</span>
<a name="line-5"></a> <span class='hs-layout'>(</span><span class='hs-varid'>tyvars</span><span class='hs-layout'>,</span><span class='hs-varid'>arg_tys</span><span class='hs-layout'>,</span><span class='hs-varid'>res_ty</span><span class='hs-layout'>,</span> <span class='hs-varid'>arity</span><span class='hs-layout'>,</span> <span class='hs-varid'>strict_sig</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>primOpSig</span> <span class='hs-varid'>prim_op</span>
<a name="line-6"></a> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-varid'>tyvars</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTys</span> <span class='hs-varid'>arg_tys</span> <span class='hs-varid'>res_ty</span><span class='hs-layout'>)</span>
<a name="line-7"></a> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInName</span> <span class='hs-varid'>gHC_PRIM</span> <span class='hs-layout'>(</span><span class='hs-varid'>primOpOcc</span> <span class='hs-varid'>prim_op</span><span class='hs-layout'>)</span>
<a name="line-8"></a> <span class='hs-layout'>(</span><span class='hs-varid'>mkPrimOpIdUnique</span> <span class='hs-layout'>(</span><span class='hs-varid'>primOpTag</span> <span class='hs-varid'>prim_op</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-9"></a> <span class='hs-layout'>(</span><span class='hs-conid'>AnId</span> <span class='hs-varid'>id</span><span class='hs-layout'>)</span> <span class='hs-conid'>UserSyntax</span>
<a name="line-10"></a> <span class='hs-varid'>id</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>PrimOpId</span> <span class='hs-varid'>prim_op</span><span class='hs-layout'>)</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-11"></a>
<a name="line-12"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
<a name="line-13"></a> <span class='hs-varop'>`setSpecInfo`</span> <span class='hs-varid'>mkSpecInfo</span> <span class='hs-layout'>(</span><span class='hs-varid'>primOpRules</span> <span class='hs-varid'>prim_op</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span>
<a name="line-14"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-varid'>arity</span>
<a name="line-15"></a> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>strict_sig</span>
<a name="line-16"></a>
<a name="line-17"></a><span class='hs-comment'>-- For each ccall we manufacture a separate CCallOpId, giving it</span>
<a name="line-18"></a><span class='hs-comment'>-- a fresh unique, a type that is correct for this particular ccall,</span>
<a name="line-19"></a><span class='hs-comment'>-- and a CCall structure that gives the correct details about calling</span>
<a name="line-20"></a><span class='hs-comment'>-- convention etc. </span>
<a name="line-21"></a><span class='hs-comment'>--</span>
<a name="line-22"></a><span class='hs-comment'>-- The *name* of this Id is a local name whose OccName gives the full</span>
<a name="line-23"></a><span class='hs-comment'>-- details of the ccall, type and all. This means that the interface </span>
<a name="line-24"></a><span class='hs-comment'>-- file reader can reconstruct a suitable Id</span>
<a name="line-25"></a>
<a name="line-26"></a><a name="mkFCallId"></a><span class='hs-definition'>mkFCallId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Unique</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ForeignCall</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-27"></a><span class='hs-definition'>mkFCallId</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>fcall</span> <span class='hs-varid'>ty</span>
<a name="line-28"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ASSERT</span><span class='hs-layout'>(</span> <span class='hs-varid'>isEmptyVarSet</span> <span class='hs-layout'>(</span><span class='hs-varid'>tyVarsOfType</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span> <span class='hs-layout'>)</span>
<a name="line-29"></a> <span class='hs-comment'>-- A CCallOpId should have no free type variables; </span>
<a name="line-30"></a> <span class='hs-comment'>-- when doing substitutions won't substitute over it</span>
<a name="line-31"></a> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>FCallId</span> <span class='hs-varid'>fcall</span><span class='hs-layout'>)</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-32"></a> <span class='hs-keyword'>where</span>
<a name="line-33"></a> <span class='hs-varid'>occ_str</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showSDoc</span> <span class='hs-layout'>(</span><span class='hs-varid'>braces</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>fcall</span> <span class='hs-varop'><+></span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-34"></a> <span class='hs-comment'>-- The "occurrence name" of a ccall is the full info about the</span>
<a name="line-35"></a> <span class='hs-comment'>-- ccall; it is encoded, but may have embedded spaces etc!</span>
<a name="line-36"></a>
<a name="line-37"></a> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkFCallName</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>occ_str</span>
<a name="line-38"></a>
<a name="line-39"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
<a name="line-40"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-varid'>arity</span>
<a name="line-41"></a> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>strict_sig</span>
<a name="line-42"></a>
<a name="line-43"></a> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-layout'>,</span> <span class='hs-varid'>tau</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tcSplitForAllTys</span> <span class='hs-varid'>ty</span>
<a name="line-44"></a> <span class='hs-layout'>(</span><span class='hs-varid'>arg_tys</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tcSplitFunTys</span> <span class='hs-varid'>tau</span>
<a name="line-45"></a> <span class='hs-varid'>arity</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>length</span> <span class='hs-varid'>arg_tys</span>
<a name="line-46"></a> <span class='hs-varid'>strict_sig</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkStrictSig</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopDmdType</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>arity</span> <span class='hs-varid'>evalDmd</span><span class='hs-layout'>)</span> <span class='hs-conid'>TopRes</span><span class='hs-layout'>)</span>
<a name="line-47"></a>
<a name="line-48"></a><span class='hs-comment'>-- Tick boxes and breakpoints are both represented as TickBoxOpIds,</span>
<a name="line-49"></a><span class='hs-comment'>-- except for the type:</span>
<a name="line-50"></a><span class='hs-comment'>--</span>
<a name="line-51"></a><span class='hs-comment'>-- a plain HPC tick box has type (State# RealWorld)</span>
<a name="line-52"></a><span class='hs-comment'>-- a breakpoint Id has type forall a.a</span>
<a name="line-53"></a><span class='hs-comment'>--</span>
<a name="line-54"></a><span class='hs-comment'>-- The breakpoint Id will be applied to a list of arbitrary free variables,</span>
<a name="line-55"></a><span class='hs-comment'>-- which is why it needs a polymorphic type.</span>
<a name="line-56"></a>
<a name="line-57"></a><a name="mkTickBoxOpId"></a><span class='hs-definition'>mkTickBoxOpId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Unique</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Module</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TickBoxId</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-58"></a><span class='hs-definition'>mkTickBoxOpId</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTickBox'</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span> <span class='hs-varid'>realWorldStatePrimTy</span>
<a name="line-59"></a>
<a name="line-60"></a><a name="mkBreakPointOpId"></a><span class='hs-definition'>mkBreakPointOpId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Unique</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Module</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TickBoxId</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-61"></a><span class='hs-definition'>mkBreakPointOpId</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTickBox'</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span> <span class='hs-varid'>ty</span>
<a name="line-62"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSigmaTy</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTyVar</span><span class='hs-keyglyph'>]</span> <span class='hs-conid'>[]</span> <span class='hs-varid'>openAlphaTy</span>
<a name="line-63"></a>
<a name="line-64"></a><a name="mkTickBox'"></a><span class='hs-definition'>mkTickBox'</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkGlobalId</span> <span class='hs-layout'>(</span><span class='hs-conid'>TickBoxOpId</span> <span class='hs-varid'>tickbox</span><span class='hs-layout'>)</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-65"></a> <span class='hs-keyword'>where</span>
<a name="line-66"></a> <span class='hs-varid'>tickbox</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>TickBox</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>ix</span>
<a name="line-67"></a> <span class='hs-varid'>occ_str</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showSDoc</span> <span class='hs-layout'>(</span><span class='hs-varid'>braces</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tickbox</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-68"></a> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTickBoxOpName</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>occ_str</span>
<a name="line-69"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{DictFuns and default methods}
%* *
%************************************************************************
Important notes about dict funs and default methods
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dict funs and default methods are *not* ImplicitIds. Their definition
involves user-written code, so we can't figure out their strictness etc
based on fixed info, as we can for constructors and record selectors (say).
We build them as LocalIds, but with External Names. This ensures that
they are taken to account by free-variable finding and dependency
analysis (e.g. CoreFVs.exprFreeVars).
Why shouldn't they be bound as GlobalIds? Because, in particular, if
they are globals, the specialiser floats dict uses above their defns,
which prevents good simplifications happening. Also the strictness
analyser treats a occurrence of a GlobalId as imported and assumes it
contains strictness in its IdInfo, which isn't true if the thing is
bound in the same module as the occurrence.
It's OK for dfuns to be LocalIds, because we form the instance-env to
pass on to the next module (md_insts) in CoreTidy, afer tidying
and globalising the top-level Ids.
BUT make sure they are *exported* LocalIds (mkExportedLocalId) so
that they aren't discarded by the occurrence analyser.
\begin{code}
<pre><a name="line-1"></a><a name="mkDefaultMethodId"></a><span class='hs-definition'>mkDefaultMethodId</span> <span class='hs-varid'>dm_name</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkExportedLocalId</span> <span class='hs-varid'>dm_name</span> <span class='hs-varid'>ty</span>
<a name="line-2"></a>
<a name="line-3"></a><a name="mkDictFunId"></a><span class='hs-definition'>mkDictFunId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-comment'>-- Name to use for the dict fun;</span>
<a name="line-4"></a> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>TyVar</span><span class='hs-keyglyph'>]</span>
<a name="line-5"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ThetaType</span>
<a name="line-6"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Class</span>
<a name="line-7"></a> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span>
<a name="line-8"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-9"></a>
<a name="line-10"></a><span class='hs-definition'>mkDictFunId</span> <span class='hs-varid'>dfun_name</span> <span class='hs-varid'>inst_tyvars</span> <span class='hs-varid'>dfun_theta</span> <span class='hs-varid'>clas</span> <span class='hs-varid'>inst_tys</span>
<a name="line-11"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkExportedLocalVar</span> <span class='hs-conid'>DFunId</span> <span class='hs-varid'>dfun_name</span> <span class='hs-varid'>dfun_ty</span> <span class='hs-varid'>vanillaIdInfo</span>
<a name="line-12"></a> <span class='hs-keyword'>where</span>
<a name="line-13"></a> <span class='hs-varid'>dfun_ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSigmaTy</span> <span class='hs-varid'>inst_tyvars</span> <span class='hs-varid'>dfun_theta</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkDictTy</span> <span class='hs-varid'>clas</span> <span class='hs-varid'>inst_tys</span><span class='hs-layout'>)</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{Un-definable}
%* *
%************************************************************************
These Ids can't be defined in Haskell. They could be defined in
unfoldings in the wired-in GHC.Prim interface file, but we'd have to
ensure that they were definitely, definitely inlined, because there is
no curried identifier for them. That's what mkCompulsoryUnfolding
does. If we had a way to get a compulsory unfolding from an interface
file, we could do that, but we don't right now.
unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
just gets expanded into a type coercion wherever it occurs. Hence we
add it as a built-in Id with an unfolding here.
The type variables we use here are "open" type variables: this means
they can unify with both unlifted and lifted types. Hence we provide
another gun with which to shoot yourself in the foot.
\begin{code}
<pre><a name="line-1"></a><a name="mkWiredInIdName"></a><span class='hs-definition'>mkWiredInIdName</span> <span class='hs-varid'>mod</span> <span class='hs-varid'>fs</span> <span class='hs-varid'>uniq</span> <span class='hs-varid'>id</span>
<a name="line-2"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInName</span> <span class='hs-varid'>mod</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkOccNameFS</span> <span class='hs-varid'>varName</span> <span class='hs-varid'>fs</span><span class='hs-layout'>)</span> <span class='hs-varid'>uniq</span> <span class='hs-layout'>(</span><span class='hs-conid'>AnId</span> <span class='hs-varid'>id</span><span class='hs-layout'>)</span> <span class='hs-conid'>UserSyntax</span>
<a name="line-3"></a>
<a name="line-4"></a><a name="unsafeCoerceName"></a><span class='hs-definition'>unsafeCoerceName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_PRIM</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"unsafeCoerce#"</span><span class='hs-layout'>)</span> <span class='hs-varid'>unsafeCoerceIdKey</span> <span class='hs-varid'>unsafeCoerceId</span>
<a name="line-5"></a><a name="nullAddrName"></a><span class='hs-definition'>nullAddrName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_PRIM</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"nullAddr#"</span><span class='hs-layout'>)</span> <span class='hs-varid'>nullAddrIdKey</span> <span class='hs-varid'>nullAddrId</span>
<a name="line-6"></a><a name="seqName"></a><span class='hs-definition'>seqName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_PRIM</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"seq"</span><span class='hs-layout'>)</span> <span class='hs-varid'>seqIdKey</span> <span class='hs-varid'>seqId</span>
<a name="line-7"></a><a name="realWorldName"></a><span class='hs-definition'>realWorldName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_PRIM</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"realWorld#"</span><span class='hs-layout'>)</span> <span class='hs-varid'>realWorldPrimIdKey</span> <span class='hs-varid'>realWorldPrimId</span>
<a name="line-8"></a><a name="lazyIdName"></a><span class='hs-definition'>lazyIdName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"lazy"</span><span class='hs-layout'>)</span> <span class='hs-varid'>lazyIdKey</span> <span class='hs-varid'>lazyId</span>
<a name="line-9"></a>
<a name="line-10"></a><a name="errorName"></a><span class='hs-definition'>errorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>gHC_ERR</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"error"</span><span class='hs-layout'>)</span> <span class='hs-varid'>errorIdKey</span> <span class='hs-varid'>eRROR_ID</span>
<a name="line-11"></a><a name="recSelErrorName"></a><span class='hs-definition'>recSelErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"recSelError"</span><span class='hs-layout'>)</span> <span class='hs-varid'>recSelErrorIdKey</span> <span class='hs-varid'>rEC_SEL_ERROR_ID</span>
<a name="line-12"></a><a name="runtimeErrorName"></a><span class='hs-definition'>runtimeErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"runtimeError"</span><span class='hs-layout'>)</span> <span class='hs-varid'>runtimeErrorIdKey</span> <span class='hs-varid'>rUNTIME_ERROR_ID</span>
<a name="line-13"></a><a name="irrefutPatErrorName"></a><span class='hs-definition'>irrefutPatErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"irrefutPatError"</span><span class='hs-layout'>)</span> <span class='hs-varid'>irrefutPatErrorIdKey</span> <span class='hs-varid'>iRREFUT_PAT_ERROR_ID</span>
<a name="line-14"></a><a name="recConErrorName"></a><span class='hs-definition'>recConErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"recConError"</span><span class='hs-layout'>)</span> <span class='hs-varid'>recConErrorIdKey</span> <span class='hs-varid'>rEC_CON_ERROR_ID</span>
<a name="line-15"></a><a name="patErrorName"></a><span class='hs-definition'>patErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"patError"</span><span class='hs-layout'>)</span> <span class='hs-varid'>patErrorIdKey</span> <span class='hs-varid'>pAT_ERROR_ID</span>
<a name="line-16"></a><a name="noMethodBindingErrorName"></a><span class='hs-definition'>noMethodBindingErrorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"noMethodBindingError"</span><span class='hs-layout'>)</span>
<a name="line-17"></a> <span class='hs-varid'>noMethodBindingErrorIdKey</span> <span class='hs-varid'>nO_METHOD_BINDING_ERROR_ID</span>
<a name="line-18"></a><a name="nonExhaustiveGuardsErrorName"></a><span class='hs-definition'>nonExhaustiveGuardsErrorName</span>
<a name="line-19"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkWiredInIdName</span> <span class='hs-varid'>cONTROL_EXCEPTION_BASE</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"nonExhaustiveGuardsError"</span><span class='hs-layout'>)</span>
<a name="line-20"></a> <span class='hs-varid'>nonExhaustiveGuardsErrorIdKey</span> <span class='hs-varid'>nON_EXHAUSTIVE_GUARDS_ERROR_ID</span>
</pre>\end{code}
\begin{code}
<pre><a name="line-1"></a><a name="unsafeCoerceId"></a><span class='hs-comment'>------------------------------------------------</span>
<a name="line-2"></a><span class='hs-comment'>-- unsafeCoerce# :: forall a b. a -> b</span>
<a name="line-3"></a><span class='hs-definition'>unsafeCoerceId</span>
<a name="line-4"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>unsafeCoerceName</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-5"></a> <span class='hs-keyword'>where</span>
<a name="line-6"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>mkCompulsoryUnfolding</span> <span class='hs-varid'>rhs</span>
<a name="line-7"></a>
<a name="line-8"></a>
<a name="line-9"></a> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>openBetaTyVar</span><span class='hs-keyglyph'>]</span>
<a name="line-10"></a> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-varid'>openAlphaTy</span> <span class='hs-varid'>openBetaTy</span><span class='hs-layout'>)</span>
<a name="line-11"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>x</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTemplateLocals</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTy</span><span class='hs-keyglyph'>]</span>
<a name="line-12"></a> <span class='hs-varid'>rhs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLams</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>openBetaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>x</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>$</span>
<a name="line-13"></a> <span class='hs-conid'>Cast</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkUnsafeCoercion</span> <span class='hs-varid'>openAlphaTy</span> <span class='hs-varid'>openBetaTy</span><span class='hs-layout'>)</span>
<a name="line-14"></a>
<a name="line-15"></a><a name="nullAddrId"></a><span class='hs-comment'>------------------------------------------------</span>
<a name="line-16"></a><span class='hs-definition'>nullAddrId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span>
<a name="line-17"></a><span class='hs-comment'>-- nullAddr# :: Addr#</span>
<a name="line-18"></a><span class='hs-comment'>-- The reason is is here is because we don't provide </span>
<a name="line-19"></a><span class='hs-comment'>-- a way to write this literal in Haskell.</span>
<a name="line-20"></a><span class='hs-definition'>nullAddrId</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>nullAddrName</span> <span class='hs-varid'>addrPrimTy</span> <span class='hs-varid'>info</span>
<a name="line-21"></a> <span class='hs-keyword'>where</span>
<a name="line-22"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span> <span class='hs-varop'>`setUnfoldingInfo`</span>
<a name="line-23"></a> <span class='hs-varid'>mkCompulsoryUnfolding</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lit</span> <span class='hs-varid'>nullAddrLit</span><span class='hs-layout'>)</span>
<a name="line-24"></a>
<a name="line-25"></a><a name="seqId"></a><span class='hs-comment'>------------------------------------------------</span>
<a name="line-26"></a><span class='hs-definition'>seqId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span> <span class='hs-comment'>-- See Note [seqId magic]</span>
<a name="line-27"></a><span class='hs-definition'>seqId</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>seqName</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-28"></a> <span class='hs-keyword'>where</span>
<a name="line-29"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>mkCompulsoryUnfolding</span> <span class='hs-varid'>rhs</span>
<a name="line-30"></a>
<a name="line-31"></a>
<a name="line-32"></a> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>alphaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>openBetaTyVar</span><span class='hs-keyglyph'>]</span>
<a name="line-33"></a> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-varid'>alphaTy</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-varid'>openBetaTy</span> <span class='hs-varid'>openBetaTy</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-34"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>y</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTemplateLocals</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>alphaTy</span><span class='hs-layout'>,</span> <span class='hs-varid'>openBetaTy</span><span class='hs-keyglyph'>]</span>
<a name="line-35"></a> <span class='hs-varid'>rhs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkLams</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>alphaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>openBetaTyVar</span><span class='hs-layout'>,</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>y</span><span class='hs-keyglyph'>]</span> <span class='hs-layout'>(</span><span class='hs-conid'>Case</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span> <span class='hs-varid'>openBetaTy</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>DEFAULT</span><span class='hs-layout'>,</span> <span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-conid'>Var</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-36"></a>
<a name="line-37"></a><a name="lazyId"></a><span class='hs-comment'>------------------------------------------------</span>
<a name="line-38"></a><span class='hs-definition'>lazyId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span> <span class='hs-comment'>-- See Note [lazyId magic]</span>
<a name="line-39"></a><span class='hs-definition'>lazyId</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>lazyIdName</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-40"></a> <span class='hs-keyword'>where</span>
<a name="line-41"></a> <span class='hs-varid'>info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noCafIdInfo</span>
<a name="line-42"></a> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkForAllTys</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>alphaTyVar</span><span class='hs-keyglyph'>]</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-varid'>alphaTy</span> <span class='hs-varid'>alphaTy</span><span class='hs-layout'>)</span>
</pre>\end{code}
Note [seqId magic]
~~~~~~~~~~~~~~~~~~
'seq' is special in several ways.
a) Its second arg can have an unboxed type
x `seq` (v +# w)
b) Its fixity is set in LoadIface.ghcPrimIface
c) It has quite a bit of desugaring magic.
See DsUtils.lhs Note [Desugaring seq (1)] and (2) and (3)
d) There is some special rule handing: Note [RULES for seq]
Note [Rules for seq]
~~~~~~~~~~~~~~~~~~~~
Roman found situations where he had
case (f n) of _ -> e
where he knew that f (which was strict in n) would terminate if n did.
Notice that the result of (f n) is discarded. So it makes sense to
transform to
case n of _ -> e
Rather than attempt some general analysis to support this, I've added
enough support that you can do this using a rewrite rule:
RULE "f/seq" forall n. seq (f n) e = seq n e
You write that rule. When GHC sees a case expression that discards
its result, it mentally transforms it to a call to 'seq' and looks for
a RULE. (This is done in Simplify.rebuildCase.) As usual, the
correctness of the rule is up to you.
To make this work, we need to be careful that the magical desugaring
done in Note [seqId magic] item (c) is *not* done on the LHS of a rule.
Or rather, we arrange to un-do it, in DsBinds.decomposeRuleLhs.
Note [lazyId magic]
~~~~~~~~~~~~~~~~~~~
lazy :: forall a?. a? -> a? (i.e. works for unboxed types too)
Used to lazify pseq: pseq a b = a `seq` lazy b
Also, no strictness: by being a built-in Id, all the info about lazyId comes from here,
not from GHC.Base.hi. This is important, because the strictness
analyser will spot it as strict!
Also no unfolding in lazyId: it gets "inlined" by a HACK in CorePrep.
It's very important to do this inlining *after* unfoldings are exposed
in the interface file. Otherwise, the unfolding for (say) pseq in the
interface file will not mention 'lazy', so if we inline 'pseq' we'll totally
miss the very thing that 'lazy' was there for in the first place.
See Trac #3259 for a real world example.
lazyId is defined in GHC.Base, so we don't *have* to inline it. If it
appears un-applied, we'll end up just calling it.
-------------------------------------------------------------
@realWorld#@ used to be a magic literal, \tr{void#}. If things get
nasty as-is, change it back to a literal (@Literal@).
voidArgId is a Local Id used simply as an argument in functions
where we just want an arg to avoid having a thunk of unlifted type.
E.g.
x = \ void :: State# RealWorld -> (# p, q #)
This comes up in strictness analysis
\begin{code}
<pre><a name="line-1"></a><a name="realWorldPrimId"></a><span class='hs-definition'>realWorldPrimId</span> <span class='hs-comment'>-- :: State# RealWorld</span>
<a name="line-2"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>realWorldName</span> <span class='hs-varid'>realWorldStatePrimTy</span>
<a name="line-3"></a> <span class='hs-layout'>(</span><span class='hs-varid'>noCafIdInfo</span> <span class='hs-varop'>`setUnfoldingInfo`</span> <span class='hs-varid'>evaldUnfolding</span><span class='hs-layout'>)</span>
<a name="line-4"></a> <span class='hs-comment'>-- The evaldUnfolding makes it look that realWorld# is evaluated</span>
<a name="line-5"></a> <span class='hs-comment'>-- which in turn makes Simplify.interestingArg return True,</span>
<a name="line-6"></a> <span class='hs-comment'>-- which in turn makes INLINE things applied to realWorld# likely</span>
<a name="line-7"></a> <span class='hs-comment'>-- to be inlined</span>
<a name="line-8"></a>
<a name="line-9"></a><a name="voidArgId"></a><span class='hs-definition'>voidArgId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span>
<a name="line-10"></a><span class='hs-definition'>voidArgId</span> <span class='hs-comment'>-- :: State# RealWorld</span>
<a name="line-11"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSysLocal</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"void"</span><span class='hs-layout'>)</span> <span class='hs-varid'>voidArgIdKey</span> <span class='hs-varid'>realWorldStatePrimTy</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection[PrelVals-error-related]{@error@ and friends; @trace@}
%* *
%************************************************************************
GHC randomly injects these into the code.
@patError@ is just a version of @error@ for pattern-matching
failures. It knows various ``codes'' which expand to longer
strings---this saves space!
@absentErr@ is a thing we put in for ``absent'' arguments. They jolly
well shouldn't be yanked on, but if one is, then you will get a
friendly message from @absentErr@ (rather than a totally random
crash).
@parError@ is a special version of @error@ which the compiler does
not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
templates, but we don't ever expect to generate code for it.
\begin{code}
<pre><a name="line-1"></a><a name="mkRuntimeErrorApp"></a><span class='hs-definition'>mkRuntimeErrorApp</span>
<a name="line-2"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Id</span> <span class='hs-comment'>-- Should be of type (forall a. Addr# -> a)</span>
<a name="line-3"></a> <span class='hs-comment'>-- where Addr# points to a UTF8 encoded string</span>
<a name="line-4"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- The type to instantiate 'a'</span>
<a name="line-5"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-comment'>-- The string to print</span>
<a name="line-6"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-7"></a>
<a name="line-8"></a><span class='hs-definition'>mkRuntimeErrorApp</span> <span class='hs-varid'>err_id</span> <span class='hs-varid'>res_ty</span> <span class='hs-varid'>err_msg</span>
<a name="line-9"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkApps</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>err_id</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span> <span class='hs-varid'>res_ty</span><span class='hs-layout'>,</span> <span class='hs-varid'>err_string</span><span class='hs-keyglyph'>]</span>
<a name="line-10"></a> <span class='hs-keyword'>where</span>
<a name="line-11"></a> <span class='hs-varid'>err_string</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lit</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkMachString</span> <span class='hs-varid'>err_msg</span><span class='hs-layout'>)</span>
<a name="line-12"></a>
<a name="line-13"></a><a name="mkImpossibleExpr"></a><span class='hs-definition'>mkImpossibleExpr</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CoreExpr</span>
<a name="line-14"></a><span class='hs-definition'>mkImpossibleExpr</span> <span class='hs-varid'>res_ty</span>
<a name="line-15"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorApp</span> <span class='hs-varid'>rUNTIME_ERROR_ID</span> <span class='hs-varid'>res_ty</span> <span class='hs-str'>"Impossible case alternative"</span>
<a name="line-16"></a>
<a name="line-17"></a><a name="rEC_SEL_ERROR_ID"></a><span class='hs-definition'>rEC_SEL_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>recSelErrorName</span>
<a name="line-18"></a><a name="rUNTIME_ERROR_ID"></a><span class='hs-definition'>rUNTIME_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>runtimeErrorName</span>
<a name="line-19"></a><a name="iRREFUT_PAT_ERROR_ID"></a><span class='hs-definition'>iRREFUT_PAT_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>irrefutPatErrorName</span>
<a name="line-20"></a><a name="rEC_CON_ERROR_ID"></a><span class='hs-definition'>rEC_CON_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>recConErrorName</span>
<a name="line-21"></a><a name="pAT_ERROR_ID"></a><span class='hs-definition'>pAT_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>patErrorName</span>
<a name="line-22"></a><a name="nO_METHOD_BINDING_ERROR_ID"></a><span class='hs-definition'>nO_METHOD_BINDING_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>noMethodBindingErrorName</span>
<a name="line-23"></a><a name="nON_EXHAUSTIVE_GUARDS_ERROR_ID"></a><span class='hs-definition'>nON_EXHAUSTIVE_GUARDS_ERROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkRuntimeErrorId</span> <span class='hs-varid'>nonExhaustiveGuardsErrorName</span>
<a name="line-24"></a>
<a name="line-25"></a><span class='hs-comment'>-- The runtime error Ids take a UTF8-encoded string as argument</span>
<a name="line-26"></a>
<a name="line-27"></a><a name="mkRuntimeErrorId"></a><span class='hs-definition'>mkRuntimeErrorId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-28"></a><span class='hs-definition'>mkRuntimeErrorId</span> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pc_bottoming_Id</span> <span class='hs-varid'>name</span> <span class='hs-varid'>runtimeErrorTy</span>
<a name="line-29"></a>
<a name="line-30"></a><a name="runtimeErrorTy"></a><span class='hs-definition'>runtimeErrorTy</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span>
<a name="line-31"></a><span class='hs-definition'>runtimeErrorTy</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSigmaTy</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTyVar</span><span class='hs-keyglyph'>]</span> <span class='hs-conid'>[]</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTy</span> <span class='hs-varid'>addrPrimTy</span> <span class='hs-varid'>openAlphaTy</span><span class='hs-layout'>)</span>
</pre>\end{code}
\begin{code}
<pre><a name="line-1"></a><a name="eRROR_ID"></a><span class='hs-definition'>eRROR_ID</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pc_bottoming_Id</span> <span class='hs-varid'>errorName</span> <span class='hs-varid'>errorTy</span>
<a name="line-2"></a>
<a name="line-3"></a><a name="errorTy"></a><span class='hs-definition'>errorTy</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span>
<a name="line-4"></a><span class='hs-definition'>errorTy</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSigmaTy</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>openAlphaTyVar</span><span class='hs-keyglyph'>]</span> <span class='hs-conid'>[]</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkFunTys</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>mkListTy</span> <span class='hs-varid'>charTy</span><span class='hs-keyglyph'>]</span> <span class='hs-varid'>openAlphaTy</span><span class='hs-layout'>)</span>
<a name="line-5"></a> <span class='hs-comment'>-- Notice the openAlphaTyVar. It says that "error" can be applied</span>
<a name="line-6"></a> <span class='hs-comment'>-- to unboxed as well as boxed types. This is OK because it never</span>
<a name="line-7"></a> <span class='hs-comment'>-- returns, so the return type is irrelevant.</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{Utilities}
%* *
%************************************************************************
\begin{code}
<pre><a name="line-1"></a><a name="pcMiscPrelId"></a><span class='hs-definition'>pcMiscPrelId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IdInfo</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-2"></a><span class='hs-definition'>pcMiscPrelId</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-3"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkVanillaGlobalWithInfo</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>info</span>
<a name="line-4"></a> <span class='hs-comment'>-- We lie and say the thing is imported; otherwise, we get into</span>
<a name="line-5"></a> <span class='hs-comment'>-- a mess with dependency analysis; e.g., core2stg may heave in</span>
<a name="line-6"></a> <span class='hs-comment'>-- random calls to GHCbase.unpackPS__. If GHCbase is the module</span>
<a name="line-7"></a> <span class='hs-comment'>-- being compiled, then it's just a matter of luck if the definition</span>
<a name="line-8"></a> <span class='hs-comment'>-- will be in "the right place" to be in scope.</span>
<a name="line-9"></a>
<a name="line-10"></a><a name="pc_bottoming_Id"></a><span class='hs-definition'>pc_bottoming_Id</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Id</span>
<a name="line-11"></a><span class='hs-comment'>-- Function of arity 1, which diverges after being given one argument</span>
<a name="line-12"></a><span class='hs-definition'>pc_bottoming_Id</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span>
<a name="line-13"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pcMiscPrelId</span> <span class='hs-varid'>name</span> <span class='hs-varid'>ty</span> <span class='hs-varid'>bottoming_info</span>
<a name="line-14"></a> <span class='hs-keyword'>where</span>
<a name="line-15"></a> <span class='hs-varid'>bottoming_info</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>vanillaIdInfo</span> <span class='hs-varop'>`setAllStrictnessInfo`</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>strict_sig</span>
<a name="line-16"></a> <span class='hs-varop'>`setArityInfo`</span> <span class='hs-num'>1</span>
<a name="line-17"></a> <span class='hs-comment'>-- Make arity and strictness agree</span>
<a name="line-18"></a>
<a name="line-19"></a> <span class='hs-comment'>-- Do *not* mark them as NoCafRefs, because they can indeed have</span>
<a name="line-20"></a> <span class='hs-comment'>-- CAF refs. For example, pAT_ERROR_ID calls GHC.Err.untangle,</span>
<a name="line-21"></a> <span class='hs-comment'>-- which has some CAFs</span>
<a name="line-22"></a> <span class='hs-comment'>-- In due course we may arrange that these error-y things are</span>
<a name="line-23"></a> <span class='hs-comment'>-- regarded by the GC as permanently live, in which case we</span>
<a name="line-24"></a> <span class='hs-comment'>-- can give them NoCaf info. As it is, any function that calls</span>
<a name="line-25"></a> <span class='hs-comment'>-- any pc_bottoming_Id will itself have CafRefs, which bloats</span>
<a name="line-26"></a> <span class='hs-comment'>-- SRTs.</span>
<a name="line-27"></a>
<a name="line-28"></a> <span class='hs-varid'>strict_sig</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkStrictSig</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkTopDmdType</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>evalDmd</span><span class='hs-keyglyph'>]</span> <span class='hs-conid'>BotRes</span><span class='hs-layout'>)</span>
<a name="line-29"></a> <span class='hs-comment'>-- These "bottom" out, no matter what their arguments</span>
</pre>\end{code}
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