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%
% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1998
%
\section[TypeRep]{Type - friends' interface}
\begin{code}
<pre><a name="line-1"></a><span class='hs-comment'>-- We expose the relevant stuff from this module via the Type module</span>
<a name="line-2"></a><span class='hs-comment'>{-# OPTIONS_HADDOCK hide #-}</span>
<a name="line-3"></a>
<a name="line-4"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>TypeRep</span> <span class='hs-layout'>(</span>
<a name="line-5"></a> <span class='hs-conid'>TyThing</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-6"></a> <span class='hs-conid'>Type</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-7"></a> <span class='hs-conid'>PredType</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- to friends</span>
<a name="line-8"></a>
<a name="line-9"></a> <span class='hs-conid'>Kind</span><span class='hs-layout'>,</span> <span class='hs-conid'>ThetaType</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- Synonyms</span>
<a name="line-10"></a>
<a name="line-11"></a> <span class='hs-varid'>funTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>funTyConName</span><span class='hs-layout'>,</span>
<a name="line-12"></a>
<a name="line-13"></a> <span class='hs-comment'>-- Pretty-printing</span>
<a name="line-14"></a> <span class='hs-varid'>pprType</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprParendType</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprTypeApp</span><span class='hs-layout'>,</span>
<a name="line-15"></a> <span class='hs-varid'>pprTyThing</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprTyThingCategory</span><span class='hs-layout'>,</span>
<a name="line-16"></a> <span class='hs-varid'>pprPred</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprTheta</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprForAll</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprThetaArrow</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprClassPred</span><span class='hs-layout'>,</span>
<a name="line-17"></a>
<a name="line-18"></a> <span class='hs-comment'>-- Kinds</span>
<a name="line-19"></a> <span class='hs-varid'>liftedTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>unliftedTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>openTypeKind</span><span class='hs-layout'>,</span>
<a name="line-20"></a> <span class='hs-varid'>argTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>ubxTupleKind</span><span class='hs-layout'>,</span>
<a name="line-21"></a> <span class='hs-varid'>isLiftedTypeKindCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>isLiftedTypeKind</span><span class='hs-layout'>,</span>
<a name="line-22"></a> <span class='hs-varid'>mkArrowKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkArrowKinds</span><span class='hs-layout'>,</span> <span class='hs-varid'>isCoercionKind</span><span class='hs-layout'>,</span>
<a name="line-23"></a> <span class='hs-varid'>coVarPred</span><span class='hs-layout'>,</span>
<a name="line-24"></a>
<a name="line-25"></a> <span class='hs-comment'>-- Kind constructors...</span>
<a name="line-26"></a> <span class='hs-varid'>liftedTypeKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>openTypeKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>unliftedTypeKindTyCon</span><span class='hs-layout'>,</span>
<a name="line-27"></a> <span class='hs-varid'>argTypeKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>ubxTupleKindTyCon</span><span class='hs-layout'>,</span>
<a name="line-28"></a>
<a name="line-29"></a> <span class='hs-comment'>-- And their names</span>
<a name="line-30"></a> <span class='hs-varid'>unliftedTypeKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>openTypeKindTyConName</span><span class='hs-layout'>,</span>
<a name="line-31"></a> <span class='hs-varid'>ubxTupleKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>argTypeKindTyConName</span><span class='hs-layout'>,</span>
<a name="line-32"></a> <span class='hs-varid'>liftedTypeKindTyConName</span><span class='hs-layout'>,</span>
<a name="line-33"></a>
<a name="line-34"></a> <span class='hs-comment'>-- Super Kinds</span>
<a name="line-35"></a> <span class='hs-varid'>tySuperKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>coSuperKind</span><span class='hs-layout'>,</span>
<a name="line-36"></a> <span class='hs-varid'>isTySuperKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>isCoSuperKind</span><span class='hs-layout'>,</span>
<a name="line-37"></a> <span class='hs-varid'>tySuperKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>coSuperKindTyCon</span><span class='hs-layout'>,</span>
<a name="line-38"></a>
<a name="line-39"></a> <span class='hs-varid'>pprKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprParendKind</span>
<a name="line-40"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-41"></a>
<a name="line-42"></a><span class='hs-cpp'>#include "HsVersions.h"</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='hs-keyword'>import</span> <span class='hs-comment'>{-# SOURCE #-}</span> <span class='hs-conid'>DataCon</span><span class='hs-layout'>(</span> <span class='hs-conid'>DataCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>dataConName</span> <span class='hs-layout'>)</span>
<a name="line-45"></a>
<a name="line-46"></a><span class='hs-comment'>-- friends:</span>
<a name="line-47"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Var</span>
<a name="line-48"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Name</span>
<a name="line-49"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>BasicTypes</span>
<a name="line-50"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>TyCon</span>
<a name="line-51"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Class</span>
<a name="line-52"></a>
<a name="line-53"></a><span class='hs-comment'>-- others</span>
<a name="line-54"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>PrelNames</span>
<a name="line-55"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Outputable</span>
<a name="line-56"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>FastString</span>
</pre>\end{code}
----------------------
A note about newtypes
----------------------
Consider
newtype N = MkN Int
Then we want N to be represented as an Int, and that's what we arrange.
The front end of the compiler [TcType.lhs] treats N as opaque,
the back end treats it as transparent [Type.lhs].
There's a bit of a problem with recursive newtypes
newtype P = MkP P
newtype Q = MkQ (Q->Q)
Here the 'implicit expansion' we get from treating P and Q as transparent
would give rise to infinite types, which in turn makes eqType diverge.
Similarly splitForAllTys and splitFunTys can get into a loop.
Solution:
* Newtypes are always represented using TyConApp.
* For non-recursive newtypes, P, treat P just like a type synonym after
type-checking is done; i.e. it's opaque during type checking (functions
from TcType) but transparent afterwards (functions from Type).
"Treat P as a type synonym" means "all functions expand NewTcApps
on the fly".
Applications of the data constructor P simply vanish:
P x = x
* For recursive newtypes Q, treat the Q and its representation as
distinct right through the compiler. Applications of the data consructor
use a coerce:
Q = \(x::Q->Q). coerce Q x
They are rare, so who cares if they are a tiny bit less efficient.
The typechecker (TcTyDecls) identifies enough type construtors as 'recursive'
to cut all loops. The other members of the loop may be marked 'non-recursive'.
%************************************************************************
%* *
\subsection{The data type}
%* *
%************************************************************************
\begin{code}
<pre><a name="line-1"></a><a name="Type"></a><span class='hs-comment'>-- | The key representation of types within the compiler</span>
<a name="line-2"></a><a name="Type"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Type</span>
<a name="line-3"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>TyVarTy</span> <span class='hs-conid'>TyVar</span> <span class='hs-comment'>-- ^ Vanilla type variable</span>
<a name="line-4"></a>
<a name="line-5"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>AppTy</span>
<a name="line-6"></a> <span class='hs-conid'>Type</span>
<a name="line-7"></a> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- ^ Type application to something other than a 'TyCon'. Parameters:</span>
<a name="line-8"></a> <span class='hs-comment'>--</span>
<a name="line-9"></a> <span class='hs-comment'>-- 1) Function: must /not/ be a 'TyConApp', must be another 'AppTy', or 'TyVarTy'</span>
<a name="line-10"></a> <span class='hs-comment'>--</span>
<a name="line-11"></a> <span class='hs-comment'>-- 2) Argument type</span>
<a name="line-12"></a>
<a name="line-13"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>TyConApp</span>
<a name="line-14"></a> <span class='hs-conid'>TyCon</span>
<a name="line-15"></a> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- ^ Application of a 'TyCon', including newtypes /and/ synonyms.</span>
<a name="line-16"></a> <span class='hs-comment'>-- Invariant: saturated appliations of 'FunTyCon' must</span>
<a name="line-17"></a> <span class='hs-comment'>-- use 'FunTy' and saturated synonyms must use their own</span>
<a name="line-18"></a> <span class='hs-comment'>-- constructors. However, /unsaturated/ 'FunTyCon's do appear as 'TyConApp's.</span>
<a name="line-19"></a> <span class='hs-comment'>-- Parameters:</span>
<a name="line-20"></a> <span class='hs-comment'>--</span>
<a name="line-21"></a> <span class='hs-comment'>-- 1) Type constructor being applied to.</span>
<a name="line-22"></a> <span class='hs-comment'>--</span>
<a name="line-23"></a> <span class='hs-comment'>-- 2) Type arguments. Might not have enough type arguments here to saturate the constructor.</span>
<a name="line-24"></a> <span class='hs-comment'>-- Even type synonyms are not necessarily saturated; for example unsaturated type synonyms</span>
<a name="line-25"></a> <span class='hs-comment'>-- can appear as the right hand side of a type synonym.</span>
<a name="line-26"></a>
<a name="line-27"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>FunTy</span>
<a name="line-28"></a> <span class='hs-conid'>Type</span>
<a name="line-29"></a> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- ^ Special case of 'TyConApp': @TyConApp FunTyCon [t1, t2]@</span>
<a name="line-30"></a>
<a name="line-31"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ForAllTy</span>
<a name="line-32"></a> <span class='hs-conid'>TyVar</span>
<a name="line-33"></a> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- ^ A polymorphic type</span>
<a name="line-34"></a>
<a name="line-35"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>PredTy</span>
<a name="line-36"></a> <span class='hs-conid'>PredType</span> <span class='hs-comment'>-- ^ The type of evidence for a type predictate.</span>
<a name="line-37"></a> <span class='hs-comment'>-- Note that a @PredTy (EqPred _ _)@ can appear only as the kind</span>
<a name="line-38"></a> <span class='hs-comment'>-- of a coercion variable; never as the argument or result</span>
<a name="line-39"></a> <span class='hs-comment'>-- of a 'FunTy' (unlike the 'PredType' constructors 'ClassP' or 'IParam')</span>
<a name="line-40"></a>
<a name="line-41"></a> <span class='hs-comment'>-- See Note [PredTy], and Note [Equality predicates]</span>
<a name="line-42"></a>
<a name="line-43"></a><a name="Kind"></a><span class='hs-comment'>-- | The key type representing kinds in the compiler.</span>
<a name="line-44"></a><a name="Kind"></a><span class='hs-comment'>-- Invariant: a kind is always in one of these forms:</span>
<a name="line-45"></a><a name="Kind"></a><span class='hs-comment'>--</span>
<a name="line-46"></a><a name="Kind"></a><span class='hs-comment'>-- > FunTy k1 k2</span>
<a name="line-47"></a><a name="Kind"></a><span class='hs-comment'>-- > TyConApp PrimTyCon [...]</span>
<a name="line-48"></a><a name="Kind"></a><span class='hs-comment'>-- > TyVar kv -- (during inference only)</span>
<a name="line-49"></a><a name="Kind"></a><span class='hs-comment'>-- > ForAll ... -- (for top-level coercions)</span>
<a name="line-50"></a><a name="Kind"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Type</span>
<a name="line-51"></a>
<a name="line-52"></a><a name="SuperKind"></a><span class='hs-comment'>-- | "Super kinds", used to help encode 'Kind's as types.</span>
<a name="line-53"></a><a name="SuperKind"></a><span class='hs-comment'>-- Invariant: a super kind is always of this form:</span>
<a name="line-54"></a><a name="SuperKind"></a><span class='hs-comment'>--</span>
<a name="line-55"></a><a name="SuperKind"></a><span class='hs-comment'>-- > TyConApp SuperKindTyCon ...</span>
<a name="line-56"></a><a name="SuperKind"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>SuperKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Type</span>
</pre>\end{code}
-------------------------------------
Note [PredTy]
\begin{code}
<pre><a name="line-1"></a><a name="PredType"></a><span class='hs-comment'>-- | A type of the form @PredTy p@ represents a value whose type is</span>
<a name="line-2"></a><a name="PredType"></a><span class='hs-comment'>-- the Haskell predicate @p@, where a predicate is what occurs before </span>
<a name="line-3"></a><a name="PredType"></a><span class='hs-comment'>-- the @=>@ in a Haskell type.</span>
<a name="line-4"></a><a name="PredType"></a><span class='hs-comment'>-- It can be expanded into its representation, but: </span>
<a name="line-5"></a><a name="PredType"></a><span class='hs-comment'>--</span>
<a name="line-6"></a><a name="PredType"></a><span class='hs-comment'>-- * The type checker must treat it as opaque</span>
<a name="line-7"></a><a name="PredType"></a><span class='hs-comment'>--</span>
<a name="line-8"></a><a name="PredType"></a><span class='hs-comment'>-- * The rest of the compiler treats it as transparent</span>
<a name="line-9"></a><a name="PredType"></a><span class='hs-comment'>--</span>
<a name="line-10"></a><a name="PredType"></a><span class='hs-comment'>-- Consider these examples:</span>
<a name="line-11"></a><a name="PredType"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><a name="PredType"></a><span class='hs-comment'>-- > f :: (Eq a) => a -> Int</span>
<a name="line-13"></a><a name="PredType"></a><span class='hs-comment'>-- > g :: (?x :: Int -> Int) => a -> Int</span>
<a name="line-14"></a><a name="PredType"></a><span class='hs-comment'>-- > h :: (r\l) => {r} => {l::Int | r}</span>
<a name="line-15"></a><a name="PredType"></a><span class='hs-comment'>--</span>
<a name="line-16"></a><a name="PredType"></a><span class='hs-comment'>-- Here the @Eq a@ and @?x :: Int -> Int@ and @r\l@ are all called \"predicates\"</span>
<a name="line-17"></a><a name="PredType"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>PredType</span>
<a name="line-18"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ClassP</span> <span class='hs-conid'>Class</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Type</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- ^ Class predicate e.g. @Eq a@</span>
<a name="line-19"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>IParam</span> <span class='hs-layout'>(</span><span class='hs-conid'>IPName</span> <span class='hs-conid'>Name</span><span class='hs-layout'>)</span> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- ^ Implicit parameter e.g. @?x :: Int@</span>
<a name="line-20"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>EqPred</span> <span class='hs-conid'>Type</span> <span class='hs-conid'>Type</span> <span class='hs-comment'>-- ^ Equality predicate e.g @ty1 ~ ty2@</span>
<a name="line-21"></a>
<a name="line-22"></a><a name="ThetaType"></a><span class='hs-comment'>-- | A collection of 'PredType's</span>
<a name="line-23"></a><a name="ThetaType"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>ThetaType</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>PredType</span><span class='hs-keyglyph'>]</span>
</pre>\end{code}
(We don't support TREX records yet, but the setup is designed
to expand to allow them.)
A Haskell qualified type, such as that for f,g,h above, is
represented using
* a FunTy for the double arrow
* with a PredTy as the function argument
The predicate really does turn into a real extra argument to the
function. If the argument has type (PredTy p) then the predicate p is
represented by evidence (a dictionary, for example, of type (predRepTy p).
Note [Equality predicates]
~~~~~~~~~~~~~~~~~~~~~~~~~~
forall a b. (a ~ S b) => a -> b
could be represented by
ForAllTy a (ForAllTy b (FunTy (PredTy (EqPred a (S b))) ...))
OR
ForAllTy a (ForAllTy b (ForAllTy (c::PredTy (EqPred a (S b))) ...))
The latter is what we do. (Unlike for class and implicit parameter
constraints, which do use FunTy.)
Reason:
* FunTy is always a *value* function
* ForAllTy is discarded at runtime
We often need to make a "wildcard" (c::PredTy..). We always use the same
name (wildCoVarName), since it's not mentioned.
%************************************************************************
%* *
TyThing
%* *
%************************************************************************
Despite the fact that DataCon has to be imported via a hi-boot route,
this module seems the right place for TyThing, because it's needed for
funTyCon and all the types in TysPrim.
\begin{code}
<pre><a name="line-1"></a><a name="TyThing"></a><span class='hs-comment'>-- | A typecheckable-thing, essentially anything that has a name</span>
<a name="line-2"></a><a name="TyThing"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>TyThing</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>AnId</span> <span class='hs-conid'>Id</span>
<a name="line-3"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ADataCon</span> <span class='hs-conid'>DataCon</span>
<a name="line-4"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ATyCon</span> <span class='hs-conid'>TyCon</span>
<a name="line-5"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>AClass</span> <span class='hs-conid'>Class</span>
<a name="line-6"></a>
<a name="line-7"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Outputable</span> <span class='hs-conid'>TyThing</span> <span class='hs-keyword'>where</span>
<a name="line-8"></a> <span class='hs-varid'>ppr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprTyThing</span>
<a name="line-9"></a>
<a name="line-10"></a><a name="pprTyThing"></a><span class='hs-definition'>pprTyThing</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyThing</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-11"></a><span class='hs-definition'>pprTyThing</span> <span class='hs-varid'>thing</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprTyThingCategory</span> <span class='hs-varid'>thing</span> <span class='hs-varop'><+></span> <span class='hs-varid'>quotes</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-layout'>(</span><span class='hs-varid'>getName</span> <span class='hs-varid'>thing</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-12"></a>
<a name="line-13"></a><a name="pprTyThingCategory"></a><span class='hs-definition'>pprTyThingCategory</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyThing</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-14"></a><span class='hs-definition'>pprTyThingCategory</span> <span class='hs-layout'>(</span><span class='hs-conid'>ATyCon</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"Type constructor"</span><span class='hs-layout'>)</span>
<a name="line-15"></a><span class='hs-definition'>pprTyThingCategory</span> <span class='hs-layout'>(</span><span class='hs-conid'>AClass</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"Class"</span><span class='hs-layout'>)</span>
<a name="line-16"></a><span class='hs-definition'>pprTyThingCategory</span> <span class='hs-layout'>(</span><span class='hs-conid'>AnId</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"Identifier"</span><span class='hs-layout'>)</span>
<a name="line-17"></a><span class='hs-definition'>pprTyThingCategory</span> <span class='hs-layout'>(</span><span class='hs-conid'>ADataCon</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"Data constructor"</span><span class='hs-layout'>)</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>NamedThing</span> <span class='hs-conid'>TyThing</span> <span class='hs-keyword'>where</span> <span class='hs-comment'>-- Can't put this with the type</span>
<a name="line-20"></a> <span class='hs-varid'>getName</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-keyglyph'>=</span> <span class='hs-varid'>getName</span> <span class='hs-varid'>id</span> <span class='hs-comment'>-- decl, because the DataCon instance</span>
<a name="line-21"></a> <span class='hs-varid'>getName</span> <span class='hs-layout'>(</span><span class='hs-conid'>ATyCon</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>getName</span> <span class='hs-varid'>tc</span> <span class='hs-comment'>-- isn't visible there</span>
<a name="line-22"></a> <span class='hs-varid'>getName</span> <span class='hs-layout'>(</span><span class='hs-conid'>AClass</span> <span class='hs-varid'>cl</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>getName</span> <span class='hs-varid'>cl</span>
<a name="line-23"></a> <span class='hs-varid'>getName</span> <span class='hs-layout'>(</span><span class='hs-conid'>ADataCon</span> <span class='hs-varid'>dc</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dataConName</span> <span class='hs-varid'>dc</span>
</pre>\end{code}
%************************************************************************
%* *
Wired-in type constructors
%* *
%************************************************************************
We define a few wired-in type constructors here to avoid module knots
\begin{code}
<pre><a name="line-1"></a><span class='hs-comment'>--------------------------</span>
<a name="line-2"></a><span class='hs-comment'>-- First the TyCons...</span>
<a name="line-3"></a>
<a name="line-4"></a><a name="funTyCon"></a><span class='hs-comment'>-- | See "Type#kind_subtyping" for details of the distinction between the 'Kind' 'TyCon's</span>
<a name="line-5"></a><span class='hs-definition'>funTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>tySuperKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>coSuperKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>liftedTypeKindTyCon</span><span class='hs-layout'>,</span>
<a name="line-6"></a> <span class='hs-varid'>openTypeKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>unliftedTypeKindTyCon</span><span class='hs-layout'>,</span>
<a name="line-7"></a> <span class='hs-varid'>ubxTupleKindTyCon</span><span class='hs-layout'>,</span> <span class='hs-varid'>argTypeKindTyCon</span>
<a name="line-8"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span>
<a name="line-9"></a><a name="funTyConName"></a><span class='hs-definition'>funTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>tySuperKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>coSuperKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>liftedTypeKindTyConName</span><span class='hs-layout'>,</span>
<a name="line-10"></a> <span class='hs-varid'>openTypeKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>unliftedTypeKindTyConName</span><span class='hs-layout'>,</span>
<a name="line-11"></a> <span class='hs-varid'>ubxTupleKindTyConName</span><span class='hs-layout'>,</span> <span class='hs-varid'>argTypeKindTyConName</span>
<a name="line-12"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span>
<a name="line-13"></a>
<a name="line-14"></a><span class='hs-definition'>funTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkFunTyCon</span> <span class='hs-varid'>funTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkArrowKinds</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>argTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>openTypeKind</span><span class='hs-keyglyph'>]</span> <span class='hs-varid'>liftedTypeKind</span><span class='hs-layout'>)</span>
<a name="line-15"></a> <span class='hs-comment'>-- You might think that (->) should have type (?? -> ? -> *), and you'd be right</span>
<a name="line-16"></a> <span class='hs-comment'>-- But if we do that we get kind errors when saying</span>
<a name="line-17"></a> <span class='hs-comment'>-- instance Control.Arrow (->)</span>
<a name="line-18"></a> <span class='hs-comment'>-- becuase the expected kind is (*->*->*). The trouble is that the</span>
<a name="line-19"></a> <span class='hs-comment'>-- expected/actual stuff in the unifier does not go contra-variant, whereas</span>
<a name="line-20"></a> <span class='hs-comment'>-- the kind sub-typing does. Sigh. It really only matters if you use (->) in</span>
<a name="line-21"></a> <span class='hs-comment'>-- a prefix way, thus: (->) Int# Int#. And this is unusual.</span>
<a name="line-22"></a>
<a name="line-23"></a>
<a name="line-24"></a><a name="tySuperKindTyCon"></a><span class='hs-definition'>tySuperKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSuperKindTyCon</span> <span class='hs-varid'>tySuperKindTyConName</span>
<a name="line-25"></a><a name="coSuperKindTyCon"></a><span class='hs-definition'>coSuperKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkSuperKindTyCon</span> <span class='hs-varid'>coSuperKindTyConName</span>
<a name="line-26"></a>
<a name="line-27"></a><a name="liftedTypeKindTyCon"></a><span class='hs-definition'>liftedTypeKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkKindTyCon</span> <span class='hs-varid'>liftedTypeKindTyConName</span>
<a name="line-28"></a><a name="openTypeKindTyCon"></a><span class='hs-definition'>openTypeKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkKindTyCon</span> <span class='hs-varid'>openTypeKindTyConName</span>
<a name="line-29"></a><a name="unliftedTypeKindTyCon"></a><span class='hs-definition'>unliftedTypeKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkKindTyCon</span> <span class='hs-varid'>unliftedTypeKindTyConName</span>
<a name="line-30"></a><a name="ubxTupleKindTyCon"></a><span class='hs-definition'>ubxTupleKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkKindTyCon</span> <span class='hs-varid'>ubxTupleKindTyConName</span>
<a name="line-31"></a><a name="argTypeKindTyCon"></a><span class='hs-definition'>argTypeKindTyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkKindTyCon</span> <span class='hs-varid'>argTypeKindTyConName</span>
<a name="line-32"></a>
<a name="line-33"></a><a name="mkKindTyCon"></a><span class='hs-definition'>mkKindTyCon</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TyCon</span>
<a name="line-34"></a><span class='hs-definition'>mkKindTyCon</span> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkVoidPrimTyCon</span> <span class='hs-varid'>name</span> <span class='hs-varid'>tySuperKind</span> <span class='hs-num'>0</span>
<a name="line-35"></a>
<a name="line-36"></a><span class='hs-comment'>--------------------------</span>
<a name="line-37"></a><span class='hs-comment'>-- ... and now their names</span>
<a name="line-38"></a>
<a name="line-39"></a><a name="tySuperKindTyConName"></a><span class='hs-definition'>tySuperKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"BOX"</span><span class='hs-layout'>)</span> <span class='hs-varid'>tySuperKindTyConKey</span> <span class='hs-varid'>tySuperKindTyCon</span>
<a name="line-40"></a><a name="coSuperKindTyConName"></a><span class='hs-definition'>coSuperKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"COERCION"</span><span class='hs-layout'>)</span> <span class='hs-varid'>coSuperKindTyConKey</span> <span class='hs-varid'>coSuperKindTyCon</span>
<a name="line-41"></a><a name="liftedTypeKindTyConName"></a><span class='hs-definition'>liftedTypeKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"*"</span><span class='hs-layout'>)</span> <span class='hs-varid'>liftedTypeKindTyConKey</span> <span class='hs-varid'>liftedTypeKindTyCon</span>
<a name="line-42"></a><a name="openTypeKindTyConName"></a><span class='hs-definition'>openTypeKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"?"</span><span class='hs-layout'>)</span> <span class='hs-varid'>openTypeKindTyConKey</span> <span class='hs-varid'>openTypeKindTyCon</span>
<a name="line-43"></a><a name="unliftedTypeKindTyConName"></a><span class='hs-definition'>unliftedTypeKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"#"</span><span class='hs-layout'>)</span> <span class='hs-varid'>unliftedTypeKindTyConKey</span> <span class='hs-varid'>unliftedTypeKindTyCon</span>
<a name="line-44"></a><a name="ubxTupleKindTyConName"></a><span class='hs-definition'>ubxTupleKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"(#)"</span><span class='hs-layout'>)</span> <span class='hs-varid'>ubxTupleKindTyConKey</span> <span class='hs-varid'>ubxTupleKindTyCon</span>
<a name="line-45"></a><a name="argTypeKindTyConName"></a><span class='hs-definition'>argTypeKindTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"??"</span><span class='hs-layout'>)</span> <span class='hs-varid'>argTypeKindTyConKey</span> <span class='hs-varid'>argTypeKindTyCon</span>
<a name="line-46"></a><span class='hs-definition'>funTyConName</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkPrimTyConName</span> <span class='hs-layout'>(</span><span class='hs-varid'>fsLit</span> <span class='hs-str'>"(->)"</span><span class='hs-layout'>)</span> <span class='hs-varid'>funTyConKey</span> <span class='hs-varid'>funTyCon</span>
<a name="line-47"></a>
<a name="line-48"></a><a name="mkPrimTyConName"></a><span class='hs-definition'>mkPrimTyConName</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>FastString</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Unique</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Name</span>
<a name="line-49"></a><span class='hs-definition'>mkPrimTyConName</span> <span class='hs-varid'>occ</span> <span class='hs-varid'>key</span> <span class='hs-varid'>tycon</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'>mkTcOccFS</span> <span class='hs-varid'>occ</span><span class='hs-layout'>)</span>
<a name="line-50"></a> <span class='hs-varid'>key</span>
<a name="line-51"></a> <span class='hs-layout'>(</span><span class='hs-conid'>ATyCon</span> <span class='hs-varid'>tycon</span><span class='hs-layout'>)</span>
<a name="line-52"></a> <span class='hs-conid'>BuiltInSyntax</span>
<a name="line-53"></a> <span class='hs-comment'>-- All of the super kinds and kinds are defined in Prim and use BuiltInSyntax,</span>
<a name="line-54"></a> <span class='hs-comment'>-- because they are never in scope in the source</span>
<a name="line-55"></a>
<a name="line-56"></a><span class='hs-comment'>------------------</span>
<a name="line-57"></a><span class='hs-comment'>-- We also need Kinds and SuperKinds, locally and in TyCon</span>
<a name="line-58"></a>
<a name="line-59"></a><a name="kindTyConType"></a><span class='hs-definition'>kindTyConType</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span>
<a name="line-60"></a><span class='hs-definition'>kindTyConType</span> <span class='hs-varid'>kind</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>TyConApp</span> <span class='hs-varid'>kind</span> <span class='hs-conid'>[]</span>
<a name="line-61"></a>
<a name="line-62"></a><a name="liftedTypeKind"></a><span class='hs-comment'>-- | See "Type#kind_subtyping" for details of the distinction between these 'Kind's</span>
<a name="line-63"></a><span class='hs-definition'>liftedTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>unliftedTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>openTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>argTypeKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>ubxTupleKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Kind</span>
<a name="line-64"></a>
<a name="line-65"></a><span class='hs-definition'>liftedTypeKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>liftedTypeKindTyCon</span>
<a name="line-66"></a><a name="unliftedTypeKind"></a><span class='hs-definition'>unliftedTypeKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>unliftedTypeKindTyCon</span>
<a name="line-67"></a><a name="openTypeKind"></a><span class='hs-definition'>openTypeKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>openTypeKindTyCon</span>
<a name="line-68"></a><a name="argTypeKind"></a><span class='hs-definition'>argTypeKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>argTypeKindTyCon</span>
<a name="line-69"></a><a name="ubxTupleKind"></a><span class='hs-definition'>ubxTupleKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>ubxTupleKindTyCon</span>
<a name="line-70"></a>
<a name="line-71"></a><a name="mkArrowKind"></a><span class='hs-comment'>-- | Given two kinds @k1@ and @k2@, creates the 'Kind' @k1 -> k2@</span>
<a name="line-72"></a><span class='hs-definition'>mkArrowKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Kind</span>
<a name="line-73"></a><span class='hs-definition'>mkArrowKind</span> <span class='hs-varid'>k1</span> <span class='hs-varid'>k2</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FunTy</span> <span class='hs-varid'>k1</span> <span class='hs-varid'>k2</span>
<a name="line-74"></a>
<a name="line-75"></a><a name="mkArrowKinds"></a><span class='hs-comment'>-- | Iterated application of 'mkArrowKind'</span>
<a name="line-76"></a><span class='hs-definition'>mkArrowKinds</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Kind</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Kind</span>
<a name="line-77"></a><span class='hs-definition'>mkArrowKinds</span> <span class='hs-varid'>arg_kinds</span> <span class='hs-varid'>result_kind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>foldr</span> <span class='hs-varid'>mkArrowKind</span> <span class='hs-varid'>result_kind</span> <span class='hs-varid'>arg_kinds</span>
<a name="line-78"></a>
<a name="line-79"></a><a name="tySuperKind"></a><span class='hs-definition'>tySuperKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>coSuperKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>SuperKind</span>
<a name="line-80"></a><span class='hs-definition'>tySuperKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>tySuperKindTyCon</span>
<a name="line-81"></a><a name="coSuperKind"></a><span class='hs-definition'>coSuperKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kindTyConType</span> <span class='hs-varid'>coSuperKindTyCon</span>
<a name="line-82"></a>
<a name="line-83"></a><a name="isTySuperKind"></a><span class='hs-definition'>isTySuperKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>SuperKind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-84"></a><span class='hs-definition'>isTySuperKind</span> <span class='hs-layout'>(</span><span class='hs-conid'>TyConApp</span> <span class='hs-varid'>kc</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>tySuperKindTyConKey</span>
<a name="line-85"></a><span class='hs-definition'>isTySuperKind</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>False</span>
<a name="line-86"></a>
<a name="line-87"></a><a name="isCoSuperKind"></a><span class='hs-definition'>isCoSuperKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>SuperKind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-88"></a><span class='hs-definition'>isCoSuperKind</span> <span class='hs-layout'>(</span><span class='hs-conid'>TyConApp</span> <span class='hs-varid'>kc</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>kc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>coSuperKindTyConKey</span>
<a name="line-89"></a><span class='hs-definition'>isCoSuperKind</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>False</span>
<a name="line-90"></a>
<a name="line-91"></a><span class='hs-comment'>-------------------</span>
<a name="line-92"></a><span class='hs-comment'>-- Lastly we need a few functions on Kinds</span>
<a name="line-93"></a>
<a name="line-94"></a><a name="isLiftedTypeKindCon"></a><span class='hs-definition'>isLiftedTypeKindCon</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-95"></a><span class='hs-definition'>isLiftedTypeKindCon</span> <span class='hs-varid'>tc</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>liftedTypeKindTyConKey</span>
<a name="line-96"></a>
<a name="line-97"></a><a name="isLiftedTypeKind"></a><span class='hs-definition'>isLiftedTypeKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-98"></a><span class='hs-definition'>isLiftedTypeKind</span> <span class='hs-layout'>(</span><span class='hs-conid'>TyConApp</span> <span class='hs-varid'>tc</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>isLiftedTypeKindCon</span> <span class='hs-varid'>tc</span>
<a name="line-99"></a><span class='hs-definition'>isLiftedTypeKind</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>False</span>
<a name="line-100"></a>
<a name="line-101"></a><a name="isCoercionKind"></a><span class='hs-definition'>isCoercionKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-102"></a><span class='hs-comment'>-- All coercions are of form (ty1 ~ ty2)</span>
<a name="line-103"></a><span class='hs-comment'>-- This function is here rather than in Coercion, </span>
<a name="line-104"></a><span class='hs-comment'>-- because it's used in a knot-tied way to enforce invariants in Var</span>
<a name="line-105"></a><span class='hs-definition'>isCoercionKind</span> <span class='hs-layout'>(</span><span class='hs-conid'>PredTy</span> <span class='hs-layout'>(</span><span class='hs-conid'>EqPred</span> <span class='hs-layout'>{</span><span class='hs-layout'>}</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>True</span>
<a name="line-106"></a><span class='hs-definition'>isCoercionKind</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>False</span>
<a name="line-107"></a>
<a name="line-108"></a><a name="coVarPred"></a><span class='hs-definition'>coVarPred</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>CoVar</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>PredType</span>
<a name="line-109"></a><span class='hs-definition'>coVarPred</span> <span class='hs-varid'>tv</span>
<a name="line-110"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ASSERT</span><span class='hs-layout'>(</span> <span class='hs-varid'>isCoVar</span> <span class='hs-varid'>tv</span> <span class='hs-layout'>)</span>
<a name="line-111"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>tyVarKind</span> <span class='hs-varid'>tv</span> <span class='hs-keyword'>of</span>
<a name="line-112"></a> <span class='hs-conid'>PredTy</span> <span class='hs-varid'>eq</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>eq</span>
<a name="line-113"></a> <span class='hs-varid'>other</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>pprPanic</span> <span class='hs-str'>"coVarPred"</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tv</span> <span class='hs-varop'>$$</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>other</span><span class='hs-layout'>)</span>
</pre>\end{code}
%************************************************************************
%* *
\subsection{The external interface}
%* *
%************************************************************************
@pprType@ is the standard @Type@ printer; the overloaded @ppr@ function is
defined to use this. @pprParendType@ is the same, except it puts
parens around the type, except for the atomic cases. @pprParendType@
works just by setting the initial context precedence very high.
\begin{code}
<pre><a name="line-1"></a><a name="Prec"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>TopPrec</span> <span class='hs-comment'>-- No parens</span>
<a name="line-2"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>FunPrec</span> <span class='hs-comment'>-- Function args; no parens for tycon apps</span>
<a name="line-3"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>TyConPrec</span> <span class='hs-comment'>-- Tycon args; no parens for atomic</span>
<a name="line-4"></a> <span class='hs-keyword'>deriving</span><span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span> <span class='hs-layout'>)</span>
<a name="line-5"></a>
<a name="line-6"></a><a name="maybeParen"></a><span class='hs-definition'>maybeParen</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-7"></a><span class='hs-definition'>maybeParen</span> <span class='hs-varid'>ctxt_prec</span> <span class='hs-varid'>inner_prec</span> <span class='hs-varid'>pretty</span>
<a name="line-8"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>ctxt_prec</span> <span class='hs-varop'><</span> <span class='hs-varid'>inner_prec</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pretty</span>
<a name="line-9"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parens</span> <span class='hs-varid'>pretty</span>
<a name="line-10"></a>
<a name="line-11"></a><a name="pprType"></a><span class='hs-comment'>------------------</span>
<a name="line-12"></a><span class='hs-definition'>pprType</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprParendType</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-13"></a><span class='hs-definition'>pprType</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>TopPrec</span> <span class='hs-varid'>ty</span>
<a name="line-14"></a><a name="pprParendType"></a><span class='hs-definition'>pprParendType</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>TyConPrec</span> <span class='hs-varid'>ty</span>
<a name="line-15"></a>
<a name="line-16"></a><a name="pprTypeApp"></a><span class='hs-definition'>pprTypeApp</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>NamedThing</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>a</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'>SDoc</span>
<a name="line-17"></a><span class='hs-comment'>-- The first arg is the tycon, or sometimes class</span>
<a name="line-18"></a><span class='hs-comment'>-- Print infix if the tycon/class looks like an operator</span>
<a name="line-19"></a><span class='hs-definition'>pprTypeApp</span> <span class='hs-varid'>tc</span> <span class='hs-varid'>tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_type_app</span> <span class='hs-conid'>TopPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>getName</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span> <span class='hs-varid'>tys</span>
<a name="line-20"></a>
<a name="line-21"></a><a name="pprPred"></a><span class='hs-comment'>------------------</span>
<a name="line-22"></a><span class='hs-definition'>pprPred</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>PredType</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-23"></a><span class='hs-definition'>pprPred</span> <span class='hs-layout'>(</span><span class='hs-conid'>ClassP</span> <span class='hs-varid'>cls</span> <span class='hs-varid'>tys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprClassPred</span> <span class='hs-varid'>cls</span> <span class='hs-varid'>tys</span>
<a name="line-24"></a><span class='hs-definition'>pprPred</span> <span class='hs-layout'>(</span><span class='hs-conid'>IParam</span> <span class='hs-varid'>ip</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>ip</span> <span class='hs-varop'><></span> <span class='hs-varid'>dcolon</span> <span class='hs-varop'><></span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>ty</span>
<a name="line-25"></a><span class='hs-definition'>pprPred</span> <span class='hs-layout'>(</span><span class='hs-conid'>EqPred</span> <span class='hs-varid'>ty1</span> <span class='hs-varid'>ty2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sep</span> <span class='hs-keyglyph'>[</span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty1</span>
<a name="line-26"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>nest</span> <span class='hs-num'>2</span> <span class='hs-layout'>(</span><span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"~"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-27"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty2</span><span class='hs-keyglyph'>]</span>
<a name="line-28"></a> <span class='hs-comment'>-- Precedence looks like (->) so that we get</span>
<a name="line-29"></a> <span class='hs-comment'>-- Maybe a ~ Bool</span>
<a name="line-30"></a> <span class='hs-comment'>-- (a->a) ~ Bool</span>
<a name="line-31"></a> <span class='hs-comment'>-- Note parens on the latter!</span>
<a name="line-32"></a>
<a name="line-33"></a><a name="pprClassPred"></a><span class='hs-definition'>pprClassPred</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Class</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'>SDoc</span>
<a name="line-34"></a><span class='hs-definition'>pprClassPred</span> <span class='hs-varid'>clas</span> <span class='hs-varid'>tys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_type_app</span> <span class='hs-conid'>TopPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>getName</span> <span class='hs-varid'>clas</span><span class='hs-layout'>)</span> <span class='hs-varid'>tys</span>
<a name="line-35"></a>
<a name="line-36"></a><a name="pprTheta"></a><span class='hs-definition'>pprTheta</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ThetaType</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-37"></a><span class='hs-definition'>pprTheta</span> <span class='hs-varid'>theta</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parens</span> <span class='hs-layout'>(</span><span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>punctuate</span> <span class='hs-varid'>comma</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>pprPred</span> <span class='hs-varid'>theta</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-38"></a>
<a name="line-39"></a><a name="pprThetaArrow"></a><span class='hs-definition'>pprThetaArrow</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ThetaType</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-40"></a><span class='hs-definition'>pprThetaArrow</span> <span class='hs-varid'>theta</span>
<a name="line-41"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>null</span> <span class='hs-varid'>theta</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>empty</span>
<a name="line-42"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parens</span> <span class='hs-layout'>(</span><span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>punctuate</span> <span class='hs-varid'>comma</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>pprPred</span> <span class='hs-varid'>theta</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varop'><+></span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"=>"</span><span class='hs-layout'>)</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='hs-comment'>------------------</span>
<a name="line-45"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Outputable</span> <span class='hs-conid'>Type</span> <span class='hs-keyword'>where</span>
<a name="line-46"></a> <span class='hs-varid'>ppr</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>ty</span>
<a name="line-47"></a>
<a name="line-48"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Outputable</span> <span class='hs-conid'>PredType</span> <span class='hs-keyword'>where</span>
<a name="line-49"></a> <span class='hs-varid'>ppr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprPred</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Outputable</span> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>OutputableBndr</span> <span class='hs-layout'>(</span><span class='hs-conid'>IPName</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-52"></a> <span class='hs-varid'>pprBndr</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>n</span> <span class='hs-comment'>-- Simple for now</span>
<a name="line-53"></a>
<a name="line-54"></a><span class='hs-comment'>------------------</span>
<a name="line-55"></a> <span class='hs-comment'>-- OK, here's the main printer</span>
<a name="line-56"></a>
<a name="line-57"></a><a name="pprKind"></a><span class='hs-definition'>pprKind</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprParendKind</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Kind</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-58"></a><span class='hs-definition'>pprKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprType</span>
<a name="line-59"></a><a name="pprParendKind"></a><span class='hs-definition'>pprParendKind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pprParendType</span>
<a name="line-60"></a>
<a name="line-61"></a><a name="ppr_type"></a><span class='hs-definition'>ppr_type</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-62"></a><span class='hs-definition'>ppr_type</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>TyVarTy</span> <span class='hs-varid'>tv</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- Note [Infix type variables]</span>
<a name="line-63"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isSymOcc</span> <span class='hs-layout'>(</span><span class='hs-varid'>getOccName</span> <span class='hs-varid'>tv</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parens</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tv</span><span class='hs-layout'>)</span>
<a name="line-64"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>tv</span>
<a name="line-65"></a><span class='hs-definition'>ppr_type</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>PredTy</span> <span class='hs-varid'>pred</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ifPprDebug</span> <span class='hs-layout'>(</span><span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"<pred>"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varop'><></span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>pred</span><span class='hs-layout'>)</span>
<a name="line-66"></a><span class='hs-definition'>ppr_type</span> <span class='hs-varid'>p</span> <span class='hs-layout'>(</span><span class='hs-conid'>TyConApp</span> <span class='hs-varid'>tc</span> <span class='hs-varid'>tys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_tc_app</span> <span class='hs-varid'>p</span> <span class='hs-varid'>tc</span> <span class='hs-varid'>tys</span>
<a name="line-67"></a>
<a name="line-68"></a><span class='hs-definition'>ppr_type</span> <span class='hs-varid'>p</span> <span class='hs-layout'>(</span><span class='hs-conid'>AppTy</span> <span class='hs-varid'>t1</span> <span class='hs-varid'>t2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybeParen</span> <span class='hs-varid'>p</span> <span class='hs-conid'>TyConPrec</span> <span class='hs-varop'>$</span>
<a name="line-69"></a> <span class='hs-varid'>pprType</span> <span class='hs-varid'>t1</span> <span class='hs-varop'><+></span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>TyConPrec</span> <span class='hs-varid'>t2</span>
<a name="line-70"></a>
<a name="line-71"></a><span class='hs-definition'>ppr_type</span> <span class='hs-varid'>p</span> <span class='hs-varid'>ty</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>ForAllTy</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_forall_type</span> <span class='hs-varid'>p</span> <span class='hs-varid'>ty</span>
<a name="line-72"></a><span class='hs-definition'>ppr_type</span> <span class='hs-varid'>p</span> <span class='hs-varid'>ty</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>FunTy</span> <span class='hs-layout'>(</span><span class='hs-conid'>PredTy</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_forall_type</span> <span class='hs-varid'>p</span> <span class='hs-varid'>ty</span>
<a name="line-73"></a>
<a name="line-74"></a><span class='hs-definition'>ppr_type</span> <span class='hs-varid'>p</span> <span class='hs-layout'>(</span><span class='hs-conid'>FunTy</span> <span class='hs-varid'>ty1</span> <span class='hs-varid'>ty2</span><span class='hs-layout'>)</span>
<a name="line-75"></a> <span class='hs-keyglyph'>=</span> <span class='hs-comment'>-- We don't want to lose synonyms, so we mustn't use splitFunTys here.</span>
<a name="line-76"></a> <span class='hs-varid'>maybeParen</span> <span class='hs-varid'>p</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varop'>$</span>
<a name="line-77"></a> <span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty1</span> <span class='hs-conop'>:</span> <span class='hs-varid'>ppr_fun_tail</span> <span class='hs-varid'>ty2</span><span class='hs-layout'>)</span>
<a name="line-78"></a> <span class='hs-keyword'>where</span>
<a name="line-79"></a> <span class='hs-varid'>ppr_fun_tail</span> <span class='hs-layout'>(</span><span class='hs-conid'>FunTy</span> <span class='hs-varid'>ty1</span> <span class='hs-varid'>ty2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>arrow</span> <span class='hs-varop'><+></span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty1</span><span class='hs-layout'>)</span> <span class='hs-conop'>:</span> <span class='hs-varid'>ppr_fun_tail</span> <span class='hs-varid'>ty2</span>
<a name="line-80"></a> <span class='hs-varid'>ppr_fun_tail</span> <span class='hs-varid'>other_ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>arrow</span> <span class='hs-varop'><+></span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>other_ty</span><span class='hs-keyglyph'>]</span>
<a name="line-81"></a>
<a name="line-82"></a><a name="ppr_forall_type"></a><span class='hs-definition'>ppr_forall_type</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-83"></a><span class='hs-definition'>ppr_forall_type</span> <span class='hs-varid'>p</span> <span class='hs-varid'>ty</span>
<a name="line-84"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybeParen</span> <span class='hs-varid'>p</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varop'>$</span>
<a name="line-85"></a> <span class='hs-varid'>sep</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>pprForAll</span> <span class='hs-varid'>tvs</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprThetaArrow</span> <span class='hs-varid'>ctxt</span><span class='hs-layout'>,</span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>tau</span><span class='hs-keyglyph'>]</span>
<a name="line-86"></a> <span class='hs-keyword'>where</span>
<a name="line-87"></a> <span class='hs-layout'>(</span><span class='hs-varid'>tvs</span><span class='hs-layout'>,</span> <span class='hs-varid'>rho</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-conid'>[]</span> <span class='hs-varid'>ty</span>
<a name="line-88"></a> <span class='hs-layout'>(</span><span class='hs-varid'>ctxt</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'>split2</span> <span class='hs-conid'>[]</span> <span class='hs-varid'>rho</span>
<a name="line-89"></a>
<a name="line-90"></a> <span class='hs-comment'>-- We need to be extra careful here as equality constraints will occur as</span>
<a name="line-91"></a> <span class='hs-comment'>-- type variables with an equality kind. So, while collecting quantified</span>
<a name="line-92"></a> <span class='hs-comment'>-- variables, we separate the coercion variables out and turn them into</span>
<a name="line-93"></a> <span class='hs-comment'>-- equality predicates.</span>
<a name="line-94"></a> <span class='hs-varid'>split1</span> <span class='hs-varid'>tvs</span> <span class='hs-layout'>(</span><span class='hs-conid'>ForAllTy</span> <span class='hs-varid'>tv</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-95"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>isCoVar</span> <span class='hs-varid'>tv</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-layout'>(</span><span class='hs-varid'>tv</span><span class='hs-conop'>:</span><span class='hs-varid'>tvs</span><span class='hs-layout'>)</span> <span class='hs-varid'>ty</span>
<a name="line-96"></a> <span class='hs-varid'>split1</span> <span class='hs-varid'>tvs</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>tvs</span><span class='hs-layout'>,</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-97"></a>
<a name="line-98"></a> <span class='hs-varid'>split2</span> <span class='hs-varid'>ps</span> <span class='hs-layout'>(</span><span class='hs-conid'>PredTy</span> <span class='hs-varid'>p</span> <span class='hs-varop'>`FunTy`</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split2</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:</span><span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-varid'>ty</span>
<a name="line-99"></a> <span class='hs-varid'>split2</span> <span class='hs-varid'>ps</span> <span class='hs-layout'>(</span><span class='hs-conid'>ForAllTy</span> <span class='hs-varid'>tv</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-100"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isCoVar</span> <span class='hs-varid'>tv</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split2</span> <span class='hs-layout'>(</span><span class='hs-varid'>coVarPred</span> <span class='hs-varid'>tv</span> <span class='hs-conop'>:</span> <span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-varid'>ty</span>
<a name="line-101"></a> <span class='hs-varid'>split2</span> <span class='hs-varid'>ps</span> <span class='hs-varid'>ty</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>ps</span><span class='hs-layout'>,</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-102"></a>
<a name="line-103"></a><a name="ppr_tc_app"></a><span class='hs-definition'>ppr_tc_app</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Prec</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'>SDoc</span>
<a name="line-104"></a><span class='hs-definition'>ppr_tc_app</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>tc</span> <span class='hs-conid'>[]</span>
<a name="line-105"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_tc</span> <span class='hs-varid'>tc</span>
<a name="line-106"></a><span class='hs-definition'>ppr_tc_app</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>tc</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>ty</span><span class='hs-keyglyph'>]</span>
<a name="line-107"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>listTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>brackets</span> <span class='hs-layout'>(</span><span class='hs-varid'>pprType</span> <span class='hs-varid'>ty</span><span class='hs-layout'>)</span>
<a name="line-108"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>parrTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"[:"</span><span class='hs-layout'>)</span> <span class='hs-varop'><></span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>ty</span> <span class='hs-varop'><></span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>":]"</span><span class='hs-layout'>)</span>
<a name="line-109"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>liftedTypeKindTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"*"</span><span class='hs-layout'>)</span>
<a name="line-110"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>unliftedTypeKindTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"#"</span><span class='hs-layout'>)</span>
<a name="line-111"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>openTypeKindTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"(?)"</span><span class='hs-layout'>)</span>
<a name="line-112"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>ubxTupleKindTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"(#)"</span><span class='hs-layout'>)</span>
<a name="line-113"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>`hasKey`</span> <span class='hs-varid'>argTypeKindTyConKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"??"</span><span class='hs-layout'>)</span>
<a name="line-114"></a>
<a name="line-115"></a><span class='hs-definition'>ppr_tc_app</span> <span class='hs-varid'>p</span> <span class='hs-varid'>tc</span> <span class='hs-varid'>tys</span>
<a name="line-116"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isTupleTyCon</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>tyConArity</span> <span class='hs-varid'>tc</span> <span class='hs-varop'>==</span> <span class='hs-varid'>length</span> <span class='hs-varid'>tys</span>
<a name="line-117"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tupleParens</span> <span class='hs-layout'>(</span><span class='hs-varid'>tupleTyConBoxity</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>punctuate</span> <span class='hs-varid'>comma</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>pprType</span> <span class='hs-varid'>tys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-118"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-119"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr_type_app</span> <span class='hs-varid'>p</span> <span class='hs-layout'>(</span><span class='hs-varid'>getName</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span> <span class='hs-varid'>tys</span>
<a name="line-120"></a>
<a name="line-121"></a><a name="ppr_type_app"></a><span class='hs-definition'>ppr_type_app</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Prec</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Name</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'>SDoc</span>
<a name="line-122"></a><span class='hs-comment'>-- Used for classes as well as types; that's why it's separate from ppr_tc_app</span>
<a name="line-123"></a><span class='hs-definition'>ppr_type_app</span> <span class='hs-varid'>p</span> <span class='hs-varid'>tc</span> <span class='hs-varid'>tys</span>
<a name="line-124"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>is_sym_occ</span> <span class='hs-comment'>-- Print infix if possible</span>
<a name="line-125"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>ty1</span><span class='hs-layout'>,</span><span class='hs-varid'>ty2</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>tys</span> <span class='hs-comment'>-- We know nothing of precedence though</span>
<a name="line-126"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybeParen</span> <span class='hs-varid'>p</span> <span class='hs-conid'>FunPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>sep</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty1</span><span class='hs-layout'>,</span>
<a name="line-127"></a> <span class='hs-varid'>pprInfixVar</span> <span class='hs-conid'>True</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span> <span class='hs-varop'><+></span> <span class='hs-varid'>ppr_type</span> <span class='hs-conid'>FunPrec</span> <span class='hs-varid'>ty2</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-128"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-129"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybeParen</span> <span class='hs-varid'>p</span> <span class='hs-conid'>TyConPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>hang</span> <span class='hs-layout'>(</span><span class='hs-varid'>pprPrefixVar</span> <span class='hs-varid'>is_sym_occ</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-130"></a> <span class='hs-num'>2</span> <span class='hs-layout'>(</span><span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>pprParendType</span> <span class='hs-varid'>tys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-131"></a> <span class='hs-keyword'>where</span>
<a name="line-132"></a> <span class='hs-varid'>is_sym_occ</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>isSymOcc</span> <span class='hs-layout'>(</span><span class='hs-varid'>getOccName</span> <span class='hs-varid'>tc</span><span class='hs-layout'>)</span>
<a name="line-133"></a>
<a name="line-134"></a><a name="ppr_tc"></a><span class='hs-definition'>ppr_tc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyCon</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span> <span class='hs-comment'>-- No brackets for SymOcc</span>
<a name="line-135"></a><span class='hs-definition'>ppr_tc</span> <span class='hs-varid'>tc</span>
<a name="line-136"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pp_nt_debug</span> <span class='hs-varop'><></span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>tc</span>
<a name="line-137"></a> <span class='hs-keyword'>where</span>
<a name="line-138"></a> <span class='hs-varid'>pp_nt_debug</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isNewTyCon</span> <span class='hs-varid'>tc</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ifPprDebug</span> <span class='hs-layout'>(</span><span class='hs-keyword'>if</span> <span class='hs-varid'>isRecursiveTyCon</span> <span class='hs-varid'>tc</span>
<a name="line-139"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"<recnt>"</span><span class='hs-layout'>)</span>
<a name="line-140"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"<nt>"</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-141"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>empty</span>
<a name="line-142"></a>
<a name="line-143"></a><a name="pprForAll"></a><span class='hs-comment'>-------------------</span>
<a name="line-144"></a><span class='hs-definition'>pprForAll</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>TyVar</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-145"></a><span class='hs-definition'>pprForAll</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>empty</span>
<a name="line-146"></a><span class='hs-definition'>pprForAll</span> <span class='hs-varid'>tvs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ptext</span> <span class='hs-layout'>(</span><span class='hs-varid'>sLit</span> <span class='hs-str'>"forall"</span><span class='hs-layout'>)</span> <span class='hs-varop'><+></span> <span class='hs-varid'>sep</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>pprTvBndr</span> <span class='hs-varid'>tvs</span><span class='hs-layout'>)</span> <span class='hs-varop'><></span> <span class='hs-varid'>dot</span>
<a name="line-147"></a>
<a name="line-148"></a><a name="pprTvBndr"></a><span class='hs-definition'>pprTvBndr</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TyVar</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SDoc</span>
<a name="line-149"></a><span class='hs-definition'>pprTvBndr</span> <span class='hs-varid'>tv</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isLiftedTypeKind</span> <span class='hs-varid'>kind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ppr</span> <span class='hs-varid'>tv</span>
<a name="line-150"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parens</span> <span class='hs-layout'>(</span><span class='hs-varid'>ppr</span> <span class='hs-varid'>tv</span> <span class='hs-varop'><+></span> <span class='hs-varid'>dcolon</span> <span class='hs-varop'><+></span> <span class='hs-varid'>pprKind</span> <span class='hs-varid'>kind</span><span class='hs-layout'>)</span>
<a name="line-151"></a> <span class='hs-keyword'>where</span>
<a name="line-152"></a> <span class='hs-varid'>kind</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>tyVarKind</span> <span class='hs-varid'>tv</span>
</pre>\end{code}
Note [Infix type variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
In Haskell 98 you can say
f :: (a ~> b) -> b
and the (~>) is considered a type variable. However, the type
pretty-printer in this module will just see (a ~> b) as
App (App (TyVarTy "~>") (TyVarTy "a")) (TyVarTy "b")
So it'll print the type in prefix form. To avoid confusion we must
remember to parenthesise the operator, thus
(~>) a b -> b
See Trac #2766.
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