Massive patch for the first months work adding System FC to GHC #34

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

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index 95d9697..46e702c 100644 (file)
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -31,22 +31,22 @@ import RnEnv                ( bindLocalNames )
 import HscTypes                ( FixityEnv )
 
 import Class           ( className, classArity, classKey, classTyVars, classSCTheta, Class )
-import Type            ( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred )
+import Type            ( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred, mkTyVarTy )
 import ErrUtils                ( dumpIfSet_dyn )
 import MkId            ( mkDictFunId )
-import DataCon         ( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys )
+import DataCon         ( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys, dataConInstOrigArgTys )
 import Maybes          ( catMaybes )
 import RdrName         ( RdrName )
 import Name            ( Name, getSrcLoc )
 import NameSet         ( duDefs )
-import Kind            ( splitKindFunTys )
+import Type            ( splitKindFunTys )
 import TyCon           ( tyConTyVars, tyConDataCons, tyConArity, tyConHasGenerics,
                          tyConStupidTheta, isProductTyCon, isDataTyCon, newTyConRhs,
                          isEnumerationTyCon, isRecursiveTyCon, TyCon
                        )
 import TcType          ( TcType, ThetaType, mkTyVarTys, mkTyConApp, tcTyConAppTyCon,
                          isUnLiftedType, mkClassPred, tyVarsOfType,
-                         isArgTypeKind, tcEqTypes, tcSplitAppTys, mkAppTys )
+                         isSubArgTypeKind, tcEqTypes, tcSplitAppTys, mkAppTys )
 import Var             ( TyVar, tyVarKind, varName )
 import VarSet          ( mkVarSet, subVarSet )
 import PrelNames
@@ -350,6 +350,10 @@ makeDerivEqns overlap_flag tycl_decls
         mk_eqn_help gla_exts new_or_data tycon deriv_tvs clas tys
 
     ------------------------------------------------------------------
+    -- data/newtype T a = ... deriving( C t1 t2 )
+    --   leads to a call to mk_eqn_help with
+    --         tycon = T, deriv_tvs = ftv(t1,t2), clas = C, tys = [t1,t2]
+
     mk_eqn_help gla_exts DataType tycon deriv_tvs clas tys
       | Just err <- checkSideConditions gla_exts tycon deriv_tvs clas tys
       = bale_out (derivingThingErr clas tys tycon (tyConTyVars tycon) err)
@@ -434,7 +438,7 @@ makeDerivEqns overlap_flag tycl_decls
                -- We must pass the superclasses; the newtype might be an instance
                -- of them in a different way than the representation type
                -- E.g.         newtype Foo a = Foo a deriving( Show, Num, Eq )
-               -- Then the Show instance is not done via isomprphism; it shows
+               -- Then the Show instance is not done via isomorphism; it shows
                --      Foo 3 as "Foo 3"
                -- The Num instance is derived via isomorphism, but the Show superclass
                -- dictionary must the Show instance for Foo, *not* the Show dictionary
@@ -568,7 +572,7 @@ mkDataTypeEqn tycon clas
     ordinary_constraints
       = [ mkClassPred clas [arg_ty] 
         | data_con <- tyConDataCons tycon,
-          arg_ty   <- dataConOrigArgTys data_con,
+          arg_ty <- dataConInstOrigArgTys data_con (map mkTyVarTy (tyConTyVars tycon)),
           not (isUnLiftedType arg_ty)  -- No constraints for unlifted types?
         ]
 
@@ -649,7 +653,7 @@ cond_typeableOK :: Condition
 --           (b) 7 or fewer args
 cond_typeableOK (gla_exts, tycon)
   | tyConArity tycon > 7                                     = Just too_many
-  | not (all (isArgTypeKind . tyVarKind) (tyConTyVars tycon)) = Just bad_kind
+  | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars tycon)) = Just bad_kind
   | otherwise                                                = Nothing
   where
     too_many = quotes (ppr tycon) <+> ptext SLIT("has too many arguments")
@@ -729,9 +733,9 @@ solveDerivEqns overlap_flag orig_eqns
     gen_soln (_, clas, tc,tyvars,deriv_rhs)
       = setSrcSpan (srcLocSpan (getSrcLoc tc)) $
        do { let inst_tys = [mkTyConApp tc (mkTyVarTys tyvars)]
-          ; theta <- addErrCtxt (derivInstCtxt [] clas inst_tys) $
+          ; theta <- addErrCtxt (derivInstCtxt1 clas inst_tys) $
                      tcSimplifyDeriv tc tyvars deriv_rhs
-          ; addErrCtxt (derivInstCtxt theta clas inst_tys) $
+          ; addErrCtxt (derivInstCtxt2 theta clas inst_tys) $
             checkValidInstance tyvars theta clas inst_tys
           ; return (sortLe (<=) theta) }       -- Canonicalise before returning the soluction
       where
@@ -952,7 +956,7 @@ genTaggeryBinds infos
 \begin{code}
 derivingThingErr clas tys tycon tyvars why
   = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr pred)],
-        parens why]
+        nest 2 (parens why)]
   where
     pred = mkClassPred clas (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars)])
 
@@ -960,8 +964,12 @@ derivCtxt :: TyCon -> SDoc
 derivCtxt tycon
   = ptext SLIT("When deriving instances for") <+> quotes (ppr tycon)
 
-derivInstCtxt theta clas inst_tys
-  = hang (ptext SLIT("In the derived instance"))
-       2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, pprClassPred clas inst_tys])
+derivInstCtxt1 clas inst_tys
+  = ptext SLIT("When deriving the instance for") <+> quotes (pprClassPred clas inst_tys)
+
+derivInstCtxt2 theta clas inst_tys
+  = vcat [ptext SLIT("In the derived instance declaration"),
+          nest 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, 
+                                                 pprClassPred clas inst_tys])]
 \end{code}