[project @ 2000-11-14 10:46:39 by simonpj]

[ghc-hetmet.git] / ghc / compiler / coreSyn / CoreFVs.lhs

diff --git a/ghc/compiler/coreSyn/CoreFVs.lhs b/ghc/compiler/coreSyn/CoreFVs.lhs
index c501255..fc0d7bd 100644 (file)
--- a/ghc/compiler/coreSyn/CoreFVs.lhs
+++ b/ghc/compiler/coreSyn/CoreFVs.lhs
@@ -5,20 +5,20 @@ Taken quite directly from the Peyton Jones/Lester paper.
 
 \begin{code}
 module CoreFVs (
+       isLocalVar, mustHaveLocalBinding,
+
        exprFreeVars, exprsFreeVars,
        exprSomeFreeVars, exprsSomeFreeVars,
-       idRuleVars, idFreeVars, 
+       idRuleVars, idFreeVars, idFreeTyVars,
        ruleSomeFreeVars, ruleSomeLhsFreeVars, ruleRhsFreeVars,
 
-       mustHaveLocalBinding,
-
        CoreExprWithFVs, CoreBindWithFVs, freeVars, freeVarsOf,
     ) where
 
 #include "HsVersions.h"
 
 import CoreSyn
-import Id              ( Id, idFreeTyVars, hasNoBinding, idSpecialisation )
+import Id              ( Id, idName, idType, isLocalId, hasNoBinding, idSpecialisation )
 import VarSet
 import Var             ( Var, isId )
 import Type            ( tyVarsOfType )
@@ -29,6 +29,29 @@ import Outputable
 
 %************************************************************************
 %*                                                                     *
+\subsection{isLocalVar}
+%*                                                                     *
+%************************************************************************
+
+@isLocalVar@ returns True of all TyVars, and of Ids that are defined in 
+this module and are not constants like data constructors and record selectors.
+These are the variables that we need to pay attention to when finding free
+variables, or doing dependency analysis.
+
+\begin{code}
+isLocalVar :: Var -> Bool
+isLocalVar v = isTyVar v || isLocalId v
+\end{code}
+
+\begin{code}
+mustHaveLocalBinding :: Var -> Bool
+-- True <=> the variable must have a binding in this module
+mustHaveLocalBinding v = isTyVar v || (isLocalId v && not (hasNoBinding v))
+\end{code}
+
+
+%************************************************************************
+%*                                                                     *
 \section{Finding the free variables of an expression}
 %*                                                                     *
 %************************************************************************
@@ -138,12 +161,19 @@ expr_fvs (Let (Rec pairs) body)
 
 
 \begin{code}
-idRuleVars ::Id -> VarSet
-idRuleVars id = ASSERT( isId id) rulesRhsFreeVars (idSpecialisation id)
-
 idFreeVars :: Id -> VarSet
 idFreeVars id = ASSERT( isId id) idRuleVars id `unionVarSet` idFreeTyVars id
 
+idFreeTyVars :: Id -> TyVarSet
+-- Only local Ids conjured up locally, can have free type variables.
+-- (During type checking top-level Ids can have free tyvars)
+idFreeTyVars id = tyVarsOfType (idType id)
+-- | isLocalId id = tyVarsOfType (idType id)
+--             | otherwise    = emptyVarSet
+
+idRuleVars ::Id -> VarSet
+idRuleVars id = ASSERT( isId id) rulesRhsFreeVars (idSpecialisation id)
+
 rulesSomeFreeVars :: InterestingVarFun -> CoreRules -> VarSet
 rulesSomeFreeVars interesting (Rules rules _)
   = foldr (unionVarSet . ruleSomeFreeVars interesting) emptyVarSet rules