X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Fspecialise%2FSpecEnv.lhs;fp=ghc%2Fcompiler%2Fspecialise%2FSpecEnv.lhs;h=2d94809c97f674823422f85cbbbf4fd3056de094;hb=26741ec416bae2c502ef00a2ba0e79050a32cb67;hp=28b306de654568ccde6bd72fac07452c2098e20e;hpb=ae45ff0e9831a0dc862a5d68d03e355d7e323c62;p=ghc-hetmet.git

diff --git a/ghc/compiler/specialise/SpecEnv.lhs b/ghc/compiler/specialise/SpecEnv.lhs
index 28b306d..2d94809 100644
--- 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