[project @ 1996-06-26 10:26:00 by partain]

[ghc-hetmet.git] / ghc / compiler / specialise / SpecEnv.lhs

diff --git a/ghc/compiler/specialise/SpecEnv.lhs b/ghc/compiler/specialise/SpecEnv.lhs
index 28b306d..2d94809 100644 (file)
--- a/ghc/compiler/specialise/SpecEnv.lhs
+++ b/ghc/compiler/specialise/SpecEnv.lhs
@@ -7,7 +7,7 @@
 #include "HsVersions.h"
 
 module SpecEnv (
-       SpecEnv(..), MatchEnv,
+       SYN_IE(SpecEnv), MatchEnv,
        nullSpecEnv, isNullSpecEnv,
        addOneToSpecEnv, lookupSpecEnv,
        specEnvToList
@@ -17,7 +17,7 @@ IMP_Ubiq()
 
 import MatchEnv
 import Type            ( matchTys, isTyVarTy )
-import Usage           ( UVar(..) )
+import Usage           ( SYN_IE(UVar) )
 \end{code}
 
 
@@ -36,6 +36,22 @@ then
 \begin{verbatim}
        f (List Int) Bool d  ===>  f' Int Bool
 \end{verbatim}
+All the stuff about how many dictionaries to discard, and what types
+to apply the specialised function to, are handled by the fact that the
+SpecEnv contains a template for the result of the specialisation.
+
+There is one more exciting case, which is dealt with in exactly the same
+way.  If the specialised value is unboxed then it is lifted at its
+definition site and unlifted at its uses.  For example:
+
+       pi :: forall a. Num a => a
+
+might have a specialisation
+
+       [Int#] ===>  (case pi' of Lift pi# -> pi#)
+
+where pi' :: Lift Int# is the specialised version of pi.
+
 
 \begin{code}
 nullSpecEnv :: SpecEnv