[project @ 2001-11-29 13:47:09 by simonpj]

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

diff --git a/ghc/compiler/basicTypes/BasicTypes.lhs b/ghc/compiler/basicTypes/BasicTypes.lhs
index 35522d3..696a4c1 100644 (file)
--- a/ghc/compiler/basicTypes/BasicTypes.lhs
+++ b/ghc/compiler/basicTypes/BasicTypes.lhs
@@ -23,6 +23,8 @@ module BasicTypes(
        Fixity(..), FixityDirection(..),
        defaultFixity, maxPrecedence, negateFixity, negatePrecedence,
 
+       IPName(..), ipNameName, mapIPName,
+
        NewOrData(..), 
 
        RecFlag(..), isRec, isNonRec,
@@ -100,6 +102,33 @@ initialVersion = 1
 
 %************************************************************************
 %*                                                                     *
+\subsection{Implicit parameter identity}
+%*                                                                     *
+%************************************************************************
+
+The @IPName@ type is here because it is used in TypeRep (i.e. very
+early in the hierarchy), but also in HsSyn.
+
+\begin{code}
+data IPName name
+  = Dupable   name     -- ?x: you can freely duplicate this implicit parameter
+  | Linear name                -- %x: you must use the splitting function to duplicate it
+  deriving( Eq, Ord )  -- Ord is used in the IP name cache finite map
+                       --      (used in HscTypes.OrigIParamCache)
+
+
+ipNameName :: IPName name -> name
+ipNameName (Dupable n) = n
+ipNameName (Linear  n) = n
+
+mapIPName :: (a->b) -> IPName a -> IPName b
+mapIPName f (Dupable n) = Dupable (f n)
+mapIPName f (Linear  n) = Linear  (f n)
+\end{code}
+
+               
+%************************************************************************
+%*                                                                     *
 \subsection[Fixity]{Fixity info}
 %*                                                                     *
 %************************************************************************