[project @ 1998-01-08 18:03:08 by simonm]

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

diff --git a/ghc/compiler/types/Kind.lhs b/ghc/compiler/types/Kind.lhs
index 0b247e4..d4fe4a3 100644 (file)
--- a/ghc/compiler/types/Kind.lhs
+++ b/ghc/compiler/types/Kind.lhs
@@ -5,46 +5,106 @@
 
 \begin{code}
 module Kind (
-       Kind(..),               -- Only visible to friends: TcKind
+        GenKind(..),   -- Only visible to friends: TcKind
+       Kind,   
 
        mkArrowKind,
        mkTypeKind,
        mkUnboxedTypeKind,
        mkBoxedTypeKind,
 
-       isSubKindOf,
-       resultKind, argKind
+       hasMoreBoxityInfo,
+       resultKind, argKind,
+
+       pprKind, pprParendKind,
+
+       isUnboxedTypeKind, isTypeKind, isBoxedTypeKind
     ) where
 
-import Ubiq{-uitous-}
+#include "HsVersions.h"
 
-import Util            ( panic )
+import Util            ( panic, assertPanic )
+import Unique          ( Unique, pprUnique )
+import BasicTypes      ( Unused )
+import Outputable
 \end{code}
 
 \begin{code}
-data Kind
+data GenKind flexi
   = TypeKind           -- Any type (incl unboxed types)
   | BoxedTypeKind      -- Any boxed type
   | UnboxedTypeKind    -- Any unboxed type
-  | ArrowKind Kind Kind
-  deriving Eq
+  | ArrowKind (GenKind flexi) (GenKind flexi)
+  | VarKind Unique flexi
+
+type Kind = GenKind Unused     -- No variables at all
+
+instance Eq (GenKind flexi) where
+  TypeKind          == TypeKind          = True
+  BoxedTypeKind     == BoxedTypeKind    = True
+  UnboxedTypeKind   == UnboxedTypeKind  = True
+  (ArrowKind j1 j2) == (ArrowKind k1 k2) = j1==k1 && j2==k2
+  (VarKind u1 _)    == (VarKind u2 _)    = u1==u2
+  k1               == k2                = False
 
 mkArrowKind      = ArrowKind
 mkTypeKind       = TypeKind
 mkUnboxedTypeKind = UnboxedTypeKind
 mkBoxedTypeKind   = BoxedTypeKind
 
-isSubKindOf :: Kind -> Kind -> Bool
+isTypeKind :: GenKind flexi -> Bool
+isTypeKind TypeKind = True
+isTypeKind other    = False
+
+isBoxedTypeKind :: GenKind flexi -> Bool
+isBoxedTypeKind BoxedTypeKind = True
+isBoxedTypeKind other         = False
+
+isUnboxedTypeKind :: GenKind flexi -> Bool
+isUnboxedTypeKind UnboxedTypeKind = True
+isUnboxedTypeKind other                  = False
+
+hasMoreBoxityInfo :: GenKind flexi -> GenKind flexi -> Bool
+
+BoxedTypeKind  `hasMoreBoxityInfo` TypeKind        = True
+BoxedTypeKind   `hasMoreBoxityInfo` BoxedTypeKind   = True
 
-BoxedTypeKind   `isSubKindOf` TypeKind = True
-UnboxedTypeKind `isSubKindOf` TypeKind = True
-kind1          `isSubKindOf` kind2    = kind1 == kind2
+UnboxedTypeKind `hasMoreBoxityInfo` TypeKind       = True
+UnboxedTypeKind `hasMoreBoxityInfo` UnboxedTypeKind = True
 
-resultKind :: Kind -> Kind     -- Get result from arrow kind
+TypeKind       `hasMoreBoxityInfo` TypeKind        = True
+
+kind1@(ArrowKind _ _) `hasMoreBoxityInfo` kind2@(ArrowKind _ _)
+  = ASSERT( if kind1 == kind2 then True
+           else pprPanic "hadMoreBoxityInfo" (ppr kind1 <> comma <+> ppr kind2) )
+    True
+       -- The two kinds can be arrow kinds; for example when unifying
+       -- (m1 Int) and (m2 Int) we end up unifying m1 and m2, which should
+       -- have the same kind.
+
+kind1          `hasMoreBoxityInfo` kind2           = False
+
+resultKind :: GenKind flexi -> GenKind flexi   -- Get result from arrow kind
 resultKind (ArrowKind _ res_kind) = res_kind
 resultKind other_kind            = panic "resultKind"
 
-argKind :: Kind -> Kind                -- Get argument from arrow kind
+argKind :: GenKind flexi -> GenKind flexi              -- Get argument from arrow kind
 argKind (ArrowKind arg_kind _) = arg_kind
 argKind other_kind            = panic "argKind"
 \end{code}
+
+Printing
+~~~~~~~~
+\begin{code}
+instance Outputable (GenKind flexi) where
+  ppr kind = pprKind kind
+
+pprKind TypeKind          = text "**"  -- Can be boxed or unboxed
+pprKind BoxedTypeKind     = char '*'
+pprKind UnboxedTypeKind   = text  "*#" -- Unboxed
+pprKind (ArrowKind k1 k2) = sep [pprParendKind k1, text "->", pprKind k2]
+pprKind (VarKind u _)     = char 'k' <> pprUnique u
+
+pprParendKind k@(ArrowKind _ _) = parens (pprKind k)
+pprParendKind k                        = pprKind k
+\end{code}