simonpj 2004/12/21 04:23:05 PST
Modified files:
ghc/compiler/coreSyn Subst.lhs
ghc/compiler/specialise Rules.lhs
ghc/compiler/typecheck Inst.lhs TcEnv.lhs TcExpr.lhs
TcHsType.lhs TcPat.lhs TcRnTypes.lhs
TcSplice.lhs TcType.lhs TcUnify.lhs
ghc/compiler/types FunDeps.lhs InstEnv.lhs Type.lhs
Unify.lhs
Log:
---------------------------------
Improve handling of lexically scoped type variables
---------------------------------
If we have
f :: T a -> a
f (x :: T b) = ...
then the lexically scoped variable 'b' should refer to the rigid
type variable 'a', without any intervening wobbliness. Previously
the in-scope type variables were always mutable TyVars, which were
instantatiated to point to the type they were bound to; but since
the advent of GADTs the intervening mutable type variable is a bad
thing.
Hence
* In the type environment, ATyVar now carries a type
* The call to refineTyVars in tc_pat on SigPatIn
finds the types by matching
* Then tcExtendTyVarEnv3 extends the type envt appropriately
Rater a lot of huff and puff, but it's quite natural for ATyVar
to contain a type.
Various other small nomenclature changes along the way.
Revision Changes Path
1.46 +5 -5 fptools/ghc/compiler/coreSyn/Subst.lhs
1.44 +2 -2 fptools/ghc/compiler/specialise/Rules.lhs
1.143 +2 -2 fptools/ghc/compiler/typecheck/Inst.lhs
1.134 +20 -17 fptools/ghc/compiler/typecheck/TcEnv.lhs
1.176 +4 -21 fptools/ghc/compiler/typecheck/TcExpr.lhs
1.17 +2 -2 fptools/ghc/compiler/typecheck/TcHsType.lhs
1.103 +51 -8 fptools/ghc/compiler/typecheck/TcPat.lhs
1.47 +10 -3 fptools/ghc/compiler/typecheck/TcRnTypes.lhs
1.47 +2 -2 fptools/ghc/compiler/typecheck/TcSplice.lhs
1.114 +2 -2 fptools/ghc/compiler/typecheck/TcType.lhs
1.59 +3 -0 fptools/ghc/compiler/typecheck/TcUnify.lhs
1.26 +4 -4 fptools/ghc/compiler/types/FunDeps.lhs
1.36 +4 -4 fptools/ghc/compiler/types/InstEnv.lhs
1.129 +13 -10 fptools/ghc/compiler/types/Type.lhs
1.18 +23 -23 fptools/ghc/compiler/types/Unify.lhs
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