[project @ 1996-03-22 09:28:55 by partain]

[ghc-hetmet.git] / ghc / compiler / yaccParser / listcomp.c

diff --git a/ghc/compiler/yaccParser/listcomp.c b/ghc/compiler/yaccParser/listcomp.c
deleted file mode 100644 (file)
index 6258869..0000000
--- a/ghc/compiler/yaccParser/listcomp.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/*
-   Implementation of optimally compiled list comprehensions using Wadler's algorithm from
-   Peyton-Jones "Implementation of Functional Programming Languages", 1987
-
-   TQ transforms a list of qualifiers (either boolean expressions or generators) into a
-   single expression which implements the list comprehension.
-
-   TE << [E || Q] >>  =  TQ <<  [E || Q] ++ [] >>
-
-   TQ << [E || p <- L1, Q]  ++  L2 >> =
-
-      h ( TE << L1 >> ) where
-                       h = us -> case us in
-                               []        ->  TE << L2 >>
-                               (u : us') ->
-                                       (TE << p >> ->  ( TQ << [E || Q]  ++  (h us') >> )) u
- */
-
-tree TQ(quals,l2)
-list quals, l2;
-{
-  tree qualh;
-  list rest;
-
-  if(tlist(quals) == lnil)
-    return(mkcons(zfexpr,l2));
-
-  qualh = (tree) lhd(quals);
-  rest = ltl(quals);
-
-  if(ttree(qualh) != qual)
-    return(mkif(qualh,TQ(rest,l2),l2));
-
-  {
-    tree h = mkident(uniqueident("Zh%d")),
-         u = mkident(uniqueident("Iu%d")),
-         us = mkident(uniqueident("Ius%d")),
-         pat = gqpat(qualh);
-
-    pbinding tq = mkppat(gqpat(qualh),TQ(rest,mkap(h,us)));
-
-
-    return(
-       mkletv(
-        mkrbind(
-          mkpbind(
-            lsing(
-              mkppat(h,
-                mklam(us,
-                  mkcasee(us,
-                    ldub(
-                      mkppat(niltree,l2),
-                      mkppat(
-                         mkcons(u,us),
-                         mkcasee(u,lsing(tq))
-/*
-  replaces the following code which elides patterns in list comprehensions a la M*****a
-
-                         mkcasee(u,
-                           ttree(pat) == ident && !isconstr(gident(pat))?
-                             lsing(tq):
-                             ldub(tq,mkppat(mkident("_"),mkap(h,us))))
-*/
-                           )))))))),
-        mkap(h,gqexp(qualh))));
-  }
-}