Add mapOccEnv

[ghc-hetmet.git] / ghc / compiler / basicTypes / FieldLabel.lhs

diff --git a/ghc/compiler/basicTypes/FieldLabel.lhs b/ghc/compiler/basicTypes/FieldLabel.lhs
index ea2ee94..b388d37 100644 (file)
--- a/ghc/compiler/basicTypes/FieldLabel.lhs
+++ b/ghc/compiler/basicTypes/FieldLabel.lhs
@@ -1,24 +1,46 @@
 %
-% (c) The AQUA Project, Glasgow University, 1996
+% (c) The AQUA Project, Glasgow University, 1996-1998
 %
 \section[FieldLabel]{The @FieldLabel@ type}
 
 \begin{code}
-#include "HsVersions.h"
+module FieldLabel(
+       FieldLabel,     -- Abstract
+
+       mkFieldLabel, 
+       fieldLabelName, fieldLabelTyCon, fieldLabelType, fieldLabelTag,
 
-module FieldLabel where
+       FieldLabelTag,
+       firstFieldLabelTag, allFieldLabelTags
+  ) where
 
-IMP_Ubiq(){-uitous-}
+#include "HsVersions.h"
 
-import Name            ( Name{-instance Eq/Outputable-}, nameUnique )
-import Type            ( SYN_IE(Type) )
+import Type( Type )
+import TyCon( TyCon )
+import Name            ( Name{-instance Eq/Outputable-}, NamedThing(..), nameUnique )
+import Outputable
+import Unique           ( Uniquable(..) )
 \end{code}
 
 \begin{code}
 data FieldLabel
-  = FieldLabel Name
-               Type
-               FieldLabelTag
+  = FieldLabel Name            -- Also used as the Name of the field selector Id
+
+               TyCon           -- Parent type constructor
+
+               Type            -- Type of the field; may have free type variables that
+                               -- are the tyvars of its parent *data* constructor, and
+                               -- those will be the same as the tyvars of its parent *type* constructor
+                               -- e.g.  data T a = MkT { op1 :: a -> a, op2 :: a -> Int }
+                               -- The type in the FieldLabel for op1 will be simply (a->a).
+
+               FieldLabelTag   -- Indicates position within constructor
+                               -- (starting with firstFieldLabelTag)
+                               --
+                               -- If the same field occurs in more than one constructor
+                               -- then it'll have a separate FieldLabel on each occasion,
+                               -- but with a single name (and presumably the same type!)
 
 type FieldLabelTag = Int
 
@@ -28,21 +50,22 @@ firstFieldLabelTag :: FieldLabelTag
 firstFieldLabelTag = 1
 
 allFieldLabelTags :: [FieldLabelTag]
-allFieldLabelTags = [1..]
+allFieldLabelTags = [firstFieldLabelTag..]
 
-fieldLabelName (FieldLabel n _  _)   = n
-fieldLabelType (FieldLabel _ ty _)   = ty
-fieldLabelTag  (FieldLabel _ _  tag) = tag
+fieldLabelName  (FieldLabel n _ _  _)   = n
+fieldLabelTyCon (FieldLabel _ tc _ _)   = tc
+fieldLabelType  (FieldLabel _ _ ty _)   = ty
+fieldLabelTag   (FieldLabel _ _ _  tag) = tag
 
 instance Eq FieldLabel where
-    (FieldLabel n1 _ _) == (FieldLabel n2 _ _) = n1 == n2
+    fl1 == fl2 = fieldLabelName fl1 == fieldLabelName fl2
 
 instance Outputable FieldLabel where
-    ppr sty (FieldLabel n _ _) = ppr sty n
+    ppr fl = ppr (fieldLabelName fl)
 
 instance NamedThing FieldLabel where
-    getName (FieldLabel n _ _) = n
+    getName = fieldLabelName
 
 instance Uniquable FieldLabel where
-    uniqueOf (FieldLabel n _ _) = nameUnique n
+    getUnique fl = nameUnique (fieldLabelName fl)
 \end{code}