%
-% (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
-module FieldLabel where
+ mkFieldLabel,
+ fieldLabelName, fieldLabelTyCon, fieldLabelType, fieldLabelTag,
-IMP_Ubiq(){-uitous-}
+ FieldLabelTag,
+ firstFieldLabelTag, allFieldLabelTags
+ ) where
-import Name --( Name{-instance Eq/Outputable-}, nameUnique )
-import Type ( SYN_IE(Type) )
+#include "HsVersions.h"
+import Type( Type )
+import TyCon( TyCon )
+import Name ( Name{-instance Eq/Outputable-}, NamedThing(..), nameUnique )
import Outputable
-import UniqFM ( SYN_IE(Uniquable) )
+import Unique ( Uniquable(..) )
\end{code}
\begin{code}
data FieldLabel
= 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 tyvar of the constructor
+ -- 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!)
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}