[project @ 2004-08-13 13:04:50 by simonmar]

[ghc-hetmet.git] / ghc / compiler / types / Type.lhs

diff --git a/ghc/compiler/types/Type.lhs b/ghc/compiler/types/Type.lhs
index bb3c670..c7e5fa2 100644 (file)
--- a/ghc/compiler/types/Type.lhs
+++ b/ghc/compiler/types/Type.lhs
@@ -12,6 +12,8 @@ module Type (
        -- Re-exports from Kind
        module Kind,
 
+       -- Re-exports from TyCon
+       PrimRep(..),
 
        mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
 
@@ -86,14 +88,12 @@ import TyCon        ( TyCon, isRecursiveTyCon, isPrimTyCon,
                  isUnboxedTupleTyCon, isUnLiftedTyCon,
                  isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs,
                  isAlgTyCon, isSynTyCon, tyConArity, 
-                 tyConKind, getSynTyConDefn, 
-                 tyConPrimRep, 
+                 tyConKind, getSynTyConDefn, PrimRep(..), tyConPrimRep,
                )
 
 -- others
 import CmdLineOpts     ( opt_DictsStrict )
 import SrcLoc          ( noSrcLoc )
-import PrimRep         ( PrimRep(..) )
 import Unique          ( Uniquable(..) )
 import Util            ( mapAccumL, seqList, lengthIs, snocView )
 import Outputable
@@ -391,13 +391,20 @@ repType (NewTcApp tc tys) = ASSERT( tys `lengthIs` tyConArity tc )
 repType ty               = ty
 
 
+-- ToDo: this could be moved to the code generator, using splitTyConApp instead
+-- of inspecting the type directly.
 typePrimRep :: Type -> PrimRep
 typePrimRep ty = case repType ty of
                   TyConApp tc _ -> tyConPrimRep tc
                   FunTy _ _     -> PtrRep
-                  AppTy _ _     -> PtrRep      -- ??
+                  AppTy _ _     -> PtrRep      -- See note below
                   TyVarTy _     -> PtrRep
                   other         -> pprPanic "typePrimRep" (ppr ty)
+       -- Types of the form 'f a' must be of kind *, not *#, so
+       -- we are guaranteed that they are represented by pointers.
+       -- The reason is that f must have kind *->*, not *->*#, because
+       -- (we claim) there is no way to constrain f's kind any other
+       -- way.
 
 -- new_type_rep doesn't ask any questions: 
 -- it just expands newtype, whether recursive or not
@@ -407,7 +414,6 @@ new_type_rep new_tycon tys = ASSERT( tys `lengthIs` tyConArity new_tycon )
 \end{code}
 
 
-
 ---------------------------------------------------------------------
                                ForAllTy
                                ~~~~~~~~