Tidy up substitutions

[ghc-hetmet.git] / compiler / simplCore / SimplEnv.lhs

diff --git a/compiler/simplCore/SimplEnv.lhs b/compiler/simplCore/SimplEnv.lhs
index f9e0484..765fd00 100644 (file)
--- a/compiler/simplCore/SimplEnv.lhs
+++ b/compiler/simplCore/SimplEnv.lhs
@@ -130,6 +130,7 @@ data SimplEnv
     }
 
 type SimplIdSubst = IdEnv SimplSR      -- IdId |--> OutExpr
+       -- See Note [Extending the Subst] in CoreSubst
 
 data SimplSR
   = DoneEx OutExpr             -- Completed term
@@ -137,6 +138,7 @@ data SimplSR
   | ContEx TvSubstEnv          -- A suspended substitution
           SimplIdSubst
           InExpr        
+
 instance Outputable SimplSR where
   ppr (DoneEx e) = ptext SLIT("DoneEx") <+> ppr e
   ppr (DoneId v) = ptext SLIT("DoneId") <+> ppr v
@@ -531,6 +533,8 @@ substIdBndr :: SimplEnv -> Id       -- Substitition and Id to transform
 --     * The substitution extended with a DoneId if unique changed
 --       In this case, the var in the DoneId is the same as the
 --       var returned
+--
+-- Exactly like CoreSubst.substIdBndr, except that the type of id_subst differs
 
 substIdBndr env@(SimplEnv { seInScope = in_scope, seIdSubst = id_subst})
            old_id
@@ -549,6 +553,7 @@ substIdBndr env@(SimplEnv { seInScope = in_scope, seIdSubst = id_subst})
 
        -- Extend the substitution if the unique has changed
        -- See the notes with substTyVarBndr for the delSubstEnv
+       -- Also see Note [Extending the Subst] in CoreSubst
     new_subst | new_id /= old_id
              = extendVarEnv id_subst old_id (DoneId new_id)
              | otherwise