\section[FieldLabel]{The @FieldLabel@ type}
\begin{code}
-module FieldLabel where
+module FieldLabel(
+ FieldLabel, -- Abstract
-#include "HsVersions.h"
+ mkFieldLabel,
+ fieldLabelName, fieldLabelTyCon, fieldLabelType, fieldLabelTag,
+
+ FieldLabelTag,
+ firstFieldLabelTag, allFieldLabelTags
+ ) where
-import {-# SOURCE #-} TypeRep( Type ) -- FieldLabel is compiled very early
+#include "HsVersions.h"
+import Type( Type )
+import TyCon( TyCon )
import Name ( Name{-instance Eq/Outputable-}, NamedThing(..), nameUnique )
import Outputable
import Unique ( Uniquable(..) )
\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).
allFieldLabelTags :: [FieldLabelTag]
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 (FieldLabel n _ _) = ppr n
+ ppr fl = ppr (fieldLabelName fl)
instance NamedThing FieldLabel where
- getName (FieldLabel n _ _) = n
+ getName = fieldLabelName
instance Uniquable FieldLabel where
- getUnique (FieldLabel n _ _) = nameUnique n
+ getUnique fl = nameUnique (fieldLabelName fl)
\end{code}