[project @ 2003-06-02 13:27:53 by simonpj]

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diff --git a/ghc/compiler/typecheck/TcIfaceSig.lhs b/ghc/compiler/typecheck/TcIfaceSig.lhs
index e1d3230..5295fec 100644 (file)
--- a/ghc/compiler/typecheck/TcIfaceSig.lhs
+++ b/ghc/compiler/typecheck/TcIfaceSig.lhs
@@ -55,8 +55,20 @@ signatures.
 tcInterfaceSigs :: [RenamedTyClDecl]   -- Ignore non-sig-decls in these decls
                -> TcM TcGblEnv
                
+-- May 2003: 
+--     NOTE 1: careful about the side-effected EPS
+--             in the two tcExtendGlobalValueEnv calls
+--     NOTE 2: no point in tying the knot with fixM; all
+--             the important knot-tying comes via the PCS global variable
+
 tcInterfaceSigs decls = 
   zapEnv (fixM (tc_interface_sigs decls)) `thenM` \ (_,sig_ids) ->
+       -- The zapEnv dramatically trims the environment, solely
+       -- to plug the space leak that would otherwise be caused
+       -- by a rich environment bound into lots of lazy thunks
+       -- The thunks are the lazily-typechecked IdInfo of the 
+       -- imported things.
+
   tcExtendGlobalValEnv sig_ids getGblEnv  `thenM` \ gbl_env ->
   returnM gbl_env
        -- We tie a knot so that the Ids read out of interfaces are in scope