<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <!--Rendered using the Haskell Html Library v0.2--> <HTML ><HEAD ><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8" ><TITLE >CoreSubst</TITLE ><LINK HREF="haddock.css" REL="stylesheet" TYPE="text/css" ><SCRIPT SRC="haddock-util.js" TYPE="text/javascript" ></SCRIPT ><SCRIPT TYPE="text/javascript" >window.onload = function () {setSynopsis("mini_CoreSubst.html")};</SCRIPT ></HEAD ><BODY ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="topbar" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD ><IMG SRC="haskell_icon.gif" WIDTH="16" HEIGHT="16" ALT=" " ></TD ><TD CLASS="title" >ghc-6.12.3: The GHC API</TD ><TD CLASS="topbut" ><A HREF="index.html" >Contents</A ></TD ><TD CLASS="topbut" ><A HREF="doc-index.html" >Index</A ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="modulebar" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD ><FONT SIZE="6" >CoreSubst</FONT ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="section4" ><B >Contents</B ></TD ></TR ><TR ><TD ><DL ><DT ><A HREF="#1" >Main data types </A ></DT ><DD ><DL ><DT ><A HREF="#2" >Substituting into expressions and related types </A ></DT ><DT ><A HREF="#3" >Operations on substitutions </A ></DT ><DT ><A HREF="#4" >Substituting and cloning binders </A ></DT ></DL ></DD ></DL ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section1" >Synopsis</TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >data</SPAN > <A HREF="#t%3ASubst" >Subst</A > </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >type</SPAN > <A HREF="#t%3ATvSubstEnv" >TvSubstEnv</A > = <A HREF="VarEnv.html#t%3ATyVarEnv" >TyVarEnv</A > <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >type</SPAN > <A HREF="#t%3AIdSubstEnv" >IdSubstEnv</A > = <A HREF="VarEnv.html#t%3AIdEnv" >IdEnv</A > <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >data</SPAN > <A HREF="#t%3AInScopeSet" >InScopeSet</A > </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AdeShadowBinds" >deShadowBinds</A > :: [<A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >] -> [<A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >]</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstTy" >substTy</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Type.html#t%3AType" >Type</A > -> <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstExpr" >substExpr</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstBind" >substBind</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >)</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstSpec" >substSpec</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="IdInfo.html#t%3ASpecInfo" >SpecInfo</A > -> <A HREF="IdInfo.html#t%3ASpecInfo" >SpecInfo</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstWorker" >substWorker</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A > -> <A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AlookupIdSubst" >lookupIdSubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AlookupTvSubst" >lookupTvSubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3ATyVar" >TyVar</A > -> <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AemptySubst" >emptySubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AmkEmptySubst" >mkEmptySubst</A > :: <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AmkSubst" >mkSubst</A > :: <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A > -> <A HREF="CoreSubst.html#t%3ATvSubstEnv" >TvSubstEnv</A > -> <A HREF="CoreSubst.html#t%3AIdSubstEnv" >IdSubstEnv</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstInScope" >substInScope</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AisEmptySubst" >isEmptySubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="../base-4.2.0.2/Data-Bool.html#t%3ABool" >Bool</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendIdSubst" >extendIdSubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendIdSubstList" >extendIdSubstList</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3AId" >Id</A >, <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendTvSubst" >extendTvSubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3ATyVar" >TyVar</A > -> <A HREF="Type.html#t%3AType" >Type</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendTvSubstList" >extendTvSubstList</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3ATyVar" >TyVar</A >, <A HREF="Type.html#t%3AType" >Type</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendSubst" >extendSubst</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSyn.html#t%3ACoreArg" >CoreArg</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendSubstList" >extendSubstList</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3AVar" >Var</A >, <A HREF="CoreSyn.html#t%3ACoreArg" >CoreArg</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AzapSubstEnv" >zapSubstEnv</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendInScope" >extendInScope</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendInScopeList" >extendInScopeList</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AVar" >Var</A >] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AextendInScopeIds" >extendInScopeIds</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AisInScope" >isInScope</A > :: <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="../base-4.2.0.2/Data-Bool.html#t%3ABool" >Bool</A ></TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstBndr" >substBndr</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="Var.html#t%3AVar" >Var</A >)</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstBndrs" >substBndrs</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AVar" >Var</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AVar" >Var</A >])</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AsubstRecBndrs" >substRecBndrs</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AcloneIdBndr" >cloneIdBndr</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="Var.html#t%3AId" >Id</A >)</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AcloneIdBndrs" >cloneIdBndrs</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AcloneRecIdBndrs" >cloneRecIdBndrs</A > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section1" ><A NAME="1" ><A NAME="1" >Main data types </A ></A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >data</SPAN > <A NAME="t:Subst" ><A NAME="t%3ASubst" ></A ></A ><B >Subst</B > </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="ndoc" ><P >A substitution environment, containing both <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > and <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > substitutions. </P ><P >Some invariants apply to how you use the substitution: </P ><P >1. <A NAME="in_scope_invariant" ><A NAME="in_scope_invariant" ></A ></A > The in-scope set contains at least those <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s and <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT >s that will be in scope <EM >after</EM > applying the substitution to a term. Precisely, the in-scope set must be a superset of the free vars of the substitution range that might possibly clash with locally-bound variables in the thing being substituted in. </P ><P >2. <A NAME="apply_once" ><A NAME="apply_once" ></A ></A > You may apply the substitution only <EM >once</EM > </P ><P >There are various ways of setting up the in-scope set such that the first of these invariants hold: </P ><UL ><LI > Arrange that the in-scope set really is all the things in scope </LI ><LI > Arrange that it's the free vars of the range of the substitution </LI ><LI > Make it empty, if you know that all the free vars of the substitution are fresh, and hence can't possibly clash </LI ></UL ></TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:Subst')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:Subst" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Outputable.html#t%3AOutputable" >Outputable</A > <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >type</SPAN > <A NAME="t:TvSubstEnv" ><A NAME="t%3ATvSubstEnv" ></A ></A ><B >TvSubstEnv</B > = <A HREF="VarEnv.html#t%3ATyVarEnv" >TyVarEnv</A > <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="doc" >A substitition of <TT ><A HREF="Type.html#t%3AType" >Type</A ></TT >s for <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT >s </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >type</SPAN > <A NAME="t:IdSubstEnv" ><A NAME="t%3AIdSubstEnv" ></A ></A ><B >IdSubstEnv</B > = <A HREF="VarEnv.html#t%3AIdEnv" >IdEnv</A > <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="doc" >An environment for substituting for <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >data</SPAN > <A NAME="t:InScopeSet" ><A NAME="t%3AInScopeSet" ></A ></A ><B >InScopeSet</B > </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="ndoc" >A set of variables that are in scope at some point </TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:InScopeSet')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:InScopeSet" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Outputable.html#t%3AOutputable" >Outputable</A > <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A ></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section2" ><A NAME="2" ><A NAME="2" >Substituting into expressions and related types </A ></A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:deShadowBinds" ><A NAME="v%3AdeShadowBinds" ></A ></A ><B >deShadowBinds</B > :: [<A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >] -> [<A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >]</TD ></TR ><TR ><TD CLASS="doc" ><P >De-shadowing the program is sometimes a useful pre-pass. It can be done simply by running over the bindings with an empty substitution, becuase substitution returns a result that has no-shadowing guaranteed. </P ><P >(Actually, within a single <EM >type</EM > there might still be shadowing, because <TT ><A HREF="CoreSubst.html#v%3AsubstTy" >substTy</A ></TT > is a no-op for the empty substitution, but that's probably OK.) </P ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substTy" ><A NAME="v%3AsubstTy" ></A ></A ><B >substTy</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Type.html#t%3AType" >Type</A > -> <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="doc" >See <TT ><A HREF="Type.html#v%3AsubstTy" >substTy</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substExpr" ><A NAME="v%3AsubstExpr" ></A ></A ><B >substExpr</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="doc" ><P >Apply a substititon to an entire <TT ><A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TT >. Rememeber, you may only apply the substitution <EM >once</EM >: see <A HREF="CoreSubst.html#apply_once" >CoreSubst</A > </P ><P >Do *not* attempt to short-cut in the case of an empty substitution! See Note [Extending the Subst] </P ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substBind" ><A NAME="v%3AsubstBind" ></A ></A ><B >substBind</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A >)</TD ></TR ><TR ><TD CLASS="doc" >Apply a substititon to an entire <TT ><A HREF="CoreSyn.html#t%3ACoreBind" >CoreBind</A ></TT >, additionally returning an updated <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > that should be used by subsequent substitutons. </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substSpec" ><A NAME="v%3AsubstSpec" ></A ></A ><B >substSpec</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="IdInfo.html#t%3ASpecInfo" >SpecInfo</A > -> <A HREF="IdInfo.html#t%3ASpecInfo" >SpecInfo</A ></TD ></TR ><TR ><TD CLASS="doc" >Substitutes for the <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s within the <TT ><A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A ></TT > given the new function <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substWorker" ><A NAME="v%3AsubstWorker" ></A ></A ><B >substWorker</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A > -> <A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A ></TD ></TR ><TR ><TD CLASS="doc" >Substitutes for the <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s within the <TT ><A HREF="IdInfo.html#t%3AWorkerInfo" >WorkerInfo</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:lookupIdSubst" ><A NAME="v%3AlookupIdSubst" ></A ></A ><B >lookupIdSubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A ></TD ></TR ><TR ><TD CLASS="doc" >Find the substitution for an <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > in the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:lookupTvSubst" ><A NAME="v%3AlookupTvSubst" ></A ></A ><B >lookupTvSubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3ATyVar" >TyVar</A > -> <A HREF="Type.html#t%3AType" >Type</A ></TD ></TR ><TR ><TD CLASS="doc" >Find the substitution for a <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > in the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section2" ><A NAME="3" ><A NAME="3" >Operations on substitutions </A ></A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:emptySubst" ><A NAME="v%3AemptySubst" ></A ></A ><B >emptySubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:mkEmptySubst" ><A NAME="v%3AmkEmptySubst" ></A ></A ><B >mkEmptySubst</B > :: <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:mkSubst" ><A NAME="v%3AmkSubst" ></A ></A ><B >mkSubst</B > :: <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A > -> <A HREF="CoreSubst.html#t%3ATvSubstEnv" >TvSubstEnv</A > -> <A HREF="CoreSubst.html#t%3AIdSubstEnv" >IdSubstEnv</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substInScope" ><A NAME="v%3AsubstInScope" ></A ></A ><B >substInScope</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSubst.html#t%3AInScopeSet" >InScopeSet</A ></TD ></TR ><TR ><TD CLASS="doc" >Find the in-scope set: see <A HREF="CoreSubst.html#in_scope_invariant" >CoreSubst</A > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:isEmptySubst" ><A NAME="v%3AisEmptySubst" ></A ></A ><B >isEmptySubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="../base-4.2.0.2/Data-Bool.html#t%3ABool" >Bool</A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendIdSubst" ><A NAME="v%3AextendIdSubst" ></A ></A ><B >extendIdSubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add a substitution for an <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > to the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT >: you must ensure that the in-scope set is such that the <A HREF="CoreSubst.html#in_scope_invariant" >CoreSubst</A > is true after extending the substitution like this </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendIdSubstList" ><A NAME="v%3AextendIdSubstList" ></A ></A ><B >extendIdSubstList</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3AId" >Id</A >, <A HREF="CoreSyn.html#t%3ACoreExpr" >CoreExpr</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Adds multiple <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > substitutions to the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT >: see also <TT ><A HREF="CoreSubst.html#v%3AextendIdSubst" >extendIdSubst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendTvSubst" ><A NAME="v%3AextendTvSubst" ></A ></A ><B >extendTvSubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3ATyVar" >TyVar</A > -> <A HREF="Type.html#t%3AType" >Type</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add a substitution for a <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > to the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT >: you must ensure that the in-scope set is such that the <A HREF="CoreSubst.html#in_scope_invariant" >CoreSubst</A > is true after extending the substitution like this </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendTvSubstList" ><A NAME="v%3AextendTvSubstList" ></A ></A ><B >extendTvSubstList</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3ATyVar" >TyVar</A >, <A HREF="Type.html#t%3AType" >Type</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Adds multiple <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > substitutions to the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT >: see also <TT ><A HREF="CoreSubst.html#v%3AextendTvSubst" >extendTvSubst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendSubst" ><A NAME="v%3AextendSubst" ></A ></A ><B >extendSubst</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSyn.html#t%3ACoreArg" >CoreArg</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add a substitution for a <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > or <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > as appropriate to the <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT > being added. See also <TT ><A HREF="CoreSubst.html#v%3AextendIdSubst" >extendIdSubst</A ></TT > and <TT ><A HREF="CoreSubst.html#v%3AextendTvSubst" >extendTvSubst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendSubstList" ><A NAME="v%3AextendSubstList" ></A ></A ><B >extendSubstList</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [(<A HREF="Var.html#t%3AVar" >Var</A >, <A HREF="CoreSyn.html#t%3ACoreArg" >CoreArg</A >)] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add a substitution for a <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT > or <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT > as appropriate to all the <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT >s being added. See also <TT ><A HREF="CoreSubst.html#v%3AextendSubst" >extendSubst</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:zapSubstEnv" ><A NAME="v%3AzapSubstEnv" ></A ></A ><B >zapSubstEnv</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Remove all substitutions for <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s and <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT >s that might have been built up while preserving the in-scope set </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendInScope" ><A NAME="v%3AextendInScope" ></A ></A ><B >extendInScope</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add the <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT > to the in-scope set: as a side effect, removes any existing substitutions for it </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendInScopeList" ><A NAME="v%3AextendInScopeList" ></A ></A ><B >extendInScopeList</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AVar" >Var</A >] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Add the <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT >s to the in-scope set: see also <TT ><A HREF="CoreSubst.html#v%3AextendInScope" >extendInScope</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:extendInScopeIds" ><A NAME="v%3AextendInScopeIds" ></A ></A ><B >extendInScopeIds</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TD ></TR ><TR ><TD CLASS="doc" >Optimized version of <TT ><A HREF="CoreSubst.html#v%3AextendInScopeList" >extendInScopeList</A ></TT > that can be used if you are certain all the things being added are <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s and hence none are <TT ><A HREF="Var.html#t%3ATyVar" >TyVar</A ></TT >s </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:isInScope" ><A NAME="v%3AisInScope" ></A ></A ><B >isInScope</B > :: <A HREF="Var.html#t%3AVar" >Var</A > -> <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="../base-4.2.0.2/Data-Bool.html#t%3ABool" >Bool</A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section2" ><A NAME="4" ><A NAME="4" >Substituting and cloning binders </A ></A ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substBndr" ><A NAME="v%3AsubstBndr" ></A ></A ><B >substBndr</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="Var.html#t%3AVar" >Var</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="Var.html#t%3AVar" >Var</A >)</TD ></TR ><TR ><TD CLASS="doc" >Substitutes a <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT > for another one according to the <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > given, returning the result and an updated <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > that should be used by subsequent substitutons. <TT ><A HREF="IdInfo.html#t%3AIdInfo" >IdInfo</A ></TT > is preserved by this process, although it is substituted into appropriately. </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substBndrs" ><A NAME="v%3AsubstBndrs" ></A ></A ><B >substBndrs</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AVar" >Var</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AVar" >Var</A >])</TD ></TR ><TR ><TD CLASS="doc" >Applies <TT ><A HREF="CoreSubst.html#v%3AsubstBndr" >substBndr</A ></TT > to a number of <TT ><A HREF="Var.html#t%3AVar" >Var</A ></TT >s, accumulating a new <TT ><A HREF="CoreSubst.html#t%3ASubst" >Subst</A ></TT > left-to-right </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:substRecBndrs" ><A NAME="v%3AsubstRecBndrs" ></A ></A ><B >substRecBndrs</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ><TR ><TD CLASS="doc" >Substitute in a mutually recursive group of <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:cloneIdBndr" ><A NAME="v%3AcloneIdBndr" ></A ></A ><B >cloneIdBndr</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> <A HREF="Var.html#t%3AId" >Id</A > -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, <A HREF="Var.html#t%3AId" >Id</A >)</TD ></TR ><TR ><TD CLASS="doc" >Very similar to <TT ><A HREF="CoreSubst.html#v%3AsubstBndr" >substBndr</A ></TT >, but it always allocates a new <TT ><A HREF="Unique.html#t%3AUnique" >Unique</A ></TT > for each variable in its output and removes all <TT ><A HREF="IdInfo.html#t%3AIdInfo" >IdInfo</A ></TT > </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:cloneIdBndrs" ><A NAME="v%3AcloneIdBndrs" ></A ></A ><B >cloneIdBndrs</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ><TR ><TD CLASS="doc" >Applies <TT ><A HREF="CoreSubst.html#v%3AcloneIdBndr" >cloneIdBndr</A ></TT > to a number of <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s, accumulating a final substitution from left to right </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:cloneRecIdBndrs" ><A NAME="v%3AcloneRecIdBndrs" ></A ></A ><B >cloneRecIdBndrs</B > :: <A HREF="CoreSubst.html#t%3ASubst" >Subst</A > -> <A HREF="UniqSupply.html#t%3AUniqSupply" >UniqSupply</A > -> [<A HREF="Var.html#t%3AId" >Id</A >] -> (<A HREF="CoreSubst.html#t%3ASubst" >Subst</A >, [<A HREF="Var.html#t%3AId" >Id</A >])</TD ></TR ><TR ><TD CLASS="doc" >Clone a mutually recursive group of <TT ><A HREF="Var.html#t%3AId" >Id</A ></TT >s </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="botbar" >Produced by <A HREF="http://www.haskell.org/haddock/" >Haddock</A > version 2.6.1</TD ></TR ></TABLE ></BODY ></HTML >