Improve External Core newtype syntax

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

diff --git a/compiler/coreSyn/MkExternalCore.lhs b/compiler/coreSyn/MkExternalCore.lhs
index ba0c198..34f39a5 100644 (file)
--- a/compiler/coreSyn/MkExternalCore.lhs
+++ b/compiler/coreSyn/MkExternalCore.lhs
@@ -84,33 +84,17 @@ collect_tdefs tcon tdefs
   | isAlgTyCon tcon = tdef: tdefs
   where
     tdef | isNewTyCon tcon = 
-                C.Newtype (qtc tcon) (map make_tbind tyvars) 
+                C.Newtype (qtc tcon) 
                   (case newTyConCo_maybe tcon of
-                     Just co -> (qtc co, 
-                        map make_tbind vs, 
-                        make_kind (mkCoKind l r))
-                       where (vs,l,r) = coercionAxiom co
+                     Just co -> qtc co
                      Nothing       -> pprPanic ("MkExternalCore: newtype tcon\
                                        should have a coercion: ") (ppr tcon))
-                   repclause 
+                  (map make_tbind tyvars) 
+                  (make_ty (snd (newTyConRhs tcon)))
          | otherwise = 
                 C.Data (qtc tcon) (map make_tbind tyvars) 
                    (map make_cdef (tyConDataCons tcon)) 
-         where repclause | isRecursiveTyCon tcon || isOpenTyCon tcon= Nothing
-                        | otherwise = Just (make_ty (snd (newTyConRhs tcon)))
     tyvars = tyConTyVars tcon
-    coercionAxiom co = 
-      case isCoercionTyCon_maybe co of
-        -- See Note [Newtype coercions] in 
-        -- types/TyCon
-        Just (arity,coKindFun) | (l,r) <- (coKindFun $ map mkTyVarTy vs) -> 
-             -- Here we eta-expand the newtype coercion,
-             -- which makes the ext-core typechecker somewhat simpler.
-            (tyvars,mkAppTys l extraVs,mkAppTys r extraVs)
-               where (vs, extraVs) = (take arity tyvars,
-                        map mkTyVarTy $ drop arity tyvars)
-        Nothing -> pprPanic "MkExternalCore: coercion tcon lacks a kind fun"
-                     (ppr tcon)
 
 collect_tdefs _ tdefs = tdefs
 
@@ -239,8 +223,8 @@ make_ty' (TyVarTy tv)        = C.Tvar (make_var_id (tyVarName tv))
 make_ty' (AppTy t1 t2)                  = C.Tapp (make_ty t1) (make_ty t2)
 make_ty' (FunTy t1 t2)                  = make_ty (TyConApp funTyCon [t1,t2])
 make_ty' (ForAllTy tv t)        = C.Tforall (make_tbind tv) (make_ty t)
-make_ty' (TyConApp tc ts)       = foldl C.Tapp (C.Tcon (qtc tc)) 
-                                        (map make_ty ts)
+make_ty' (TyConApp tc ts)       = make_tyConApp tc ts
+
 -- Newtypes are treated just like any other type constructor; not expanded
 -- Reason: predTypeRep does substitution and, while substitution deals
 --        correctly with name capture, it's only correct if you see the uniques!
@@ -255,6 +239,25 @@ make_ty' (TyConApp tc ts)   = foldl C.Tapp (C.Tcon (qtc tc))
 
 make_ty' (PredTy p)    = make_ty (predTypeRep p)
 
+make_tyConApp :: TyCon -> [Type] -> C.Ty
+make_tyConApp tc [t1, t2] | tc == transCoercionTyCon =
+  C.TransCoercion (make_ty t1) (make_ty t2)
+make_tyConApp tc [t]      | tc == symCoercionTyCon =
+  C.SymCoercion (make_ty t)
+make_tyConApp tc [t1, t2] | tc == unsafeCoercionTyCon =
+  C.UnsafeCoercion (make_ty t1) (make_ty t2)
+make_tyConApp tc [t]      | tc == leftCoercionTyCon =
+  C.LeftCoercion (make_ty t)
+make_tyConApp tc [t]      | tc == rightCoercionTyCon =
+  C.RightCoercion (make_ty t)
+make_tyConApp tc [t1, t2] | tc == instCoercionTyCon =
+  C.InstCoercion (make_ty t1) (make_ty t2)
+-- this fails silently if we have an application
+-- of a wired-in coercion tycon to the wrong number of args.
+-- Not great...
+make_tyConApp tc ts =
+  foldl C.Tapp (C.Tcon (qtc tc)) 
+           (map make_ty ts)
 
 
 make_kind :: Kind -> C.Kind