[project @ 2001-05-21 09:19:14 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcMonoType.lhs

diff --git a/ghc/compiler/typecheck/TcMonoType.lhs b/ghc/compiler/typecheck/TcMonoType.lhs
index 0864781..bc42127 100644 (file)
--- a/ghc/compiler/typecheck/TcMonoType.lhs
+++ b/ghc/compiler/typecheck/TcMonoType.lhs
@@ -10,8 +10,9 @@ module TcMonoType ( tcHsType, tcHsRecType, tcIfaceType,
 
                        -- Kind checking
                    kcHsTyVar, kcHsTyVars, mkTyClTyVars,
-                   kcHsType, kcHsSigType, kcHsLiftedSigType, kcHsContext,
-                   tcTyVars, tcHsTyVars, mkImmutTyVars,
+                   kcHsType, kcHsSigType, kcHsSigTypes, 
+                   kcHsLiftedSigType, kcHsContext,
+                   tcScopedTyVars, tcHsTyVars, mkImmutTyVars,
 
                    TcSigInfo(..), tcTySig, mkTcSig, maybeSig,
                    checkSigTyVars, sigCtxt, sigPatCtxt
@@ -30,7 +31,7 @@ import TcEnv          ( tcExtendTyVarEnv, tcLookup, tcLookupGlobal,
                          TyThing(..), TcTyThing(..), tcExtendKindEnv
                        )
 import TcType          ( TcKind, TcTyVar, TcThetaType, TcTauType,
-                         newKindVar, tcInstSigVar,
+                         newKindVar, tcInstSigVars,
                          zonkKindEnv, zonkTcType, zonkTcTyVars, zonkTcTyVar
                        )
 import Inst            ( Inst, InstOrigin(..), newMethodWithGivenTy, instToId )
@@ -117,6 +118,10 @@ But equally valid would be
                                a::(*->*)-> *, b::*->*
 
 \begin{code}
+-- tcHsTyVars is used for type variables in type signatures
+--     e.g. forall a. a->a
+-- They are immutable, because they scope only over the signature
+-- They may or may not be explicitly-kinded
 tcHsTyVars :: [HsTyVarBndr Name] 
           -> TcM a                             -- The kind checker
           -> ([TyVar] -> TcM b)
@@ -134,16 +139,22 @@ tcHsTyVars tv_names kind_check thing_inside
     in
     tcExtendTyVarEnv tyvars (thing_inside tyvars)
 
-tcTyVars :: [Name] 
-            -> TcM a                           -- The kind checker
-            -> TcM [TyVar]
-tcTyVars [] kind_check = returnTc []
-
-tcTyVars tv_names kind_check
+-- tcScopedTyVars is used for scoped type variables
+--     e.g.  \ (x::a) (y::a) -> x+y
+-- They never have explicit kinds (because this is source-code only)
+-- They are mutable (because they can get bound to a more specific type)
+tcScopedTyVars :: [Name] 
+              -> TcM a                         -- The kind checker
+              -> TcM b
+              -> TcM b
+tcScopedTyVars [] kind_check thing_inside = thing_inside
+
+tcScopedTyVars tv_names kind_check thing_inside
   = mapNF_Tc newNamedKindVar tv_names          `thenTc` \ kind_env ->
     tcExtendKindEnv kind_env kind_check                `thenTc_`
     zonkKindEnv kind_env                       `thenNF_Tc` \ tvs_w_kinds ->
-    listNF_Tc [tcNewSigTyVar name kind | (name,kind) <- tvs_w_kinds]
+    listTc [tcNewMutTyVar name kind | (name, kind) <- tvs_w_kinds]     `thenNF_Tc` \ tyvars ->
+    tcExtendTyVarEnv tyvars thing_inside
 \end{code}
     
 
@@ -178,7 +189,8 @@ kcTypeType ty
 ---------------------------
 kcHsSigType, kcHsLiftedSigType :: RenamedHsType -> TcM ()
        -- Used for type signatures
-kcHsSigType     = kcTypeType
+kcHsSigType      = kcTypeType
+kcHsSigTypes tys  = mapTc_ kcHsSigType tys
 kcHsLiftedSigType = kcLiftedType
 
 ---------------------------
@@ -682,7 +694,7 @@ mkTcSig poly_id src_loc
    let
        (tyvars, rho) = splitForAllTys (idType poly_id)
    in
-   mapNF_Tc tcInstSigVar tyvars                `thenNF_Tc` \ tyvars' ->
+   tcInstSigVars tyvars                        `thenNF_Tc` \ tyvars' ->
        -- Make *signature* type variables
 
    let