[project @ 2000-05-31 15:44:29 by simonmar]

Incorporate Josef's patch to fix the bogus warning about overlapping
string patterns.  Thanks Josef!

diff --git a/ghc/compiler/deSugar/DsUtils.lhs b/ghc/compiler/deSugar/DsUtils.lhs
index cdd1fd3..c96665f 100644 (file)
--- a/ghc/compiler/deSugar/DsUtils.lhs
+++ b/ghc/compiler/deSugar/DsUtils.lhs
@@ -91,11 +91,8 @@ tidyLitPat lit lit_ty default_pat
   | lit_ty == floatTy            = ConPat floatDataCon  lit_ty [] [] [LitPat (mk_float lit)  floatPrimTy]
   | lit_ty == doubleTy           = ConPat doubleDataCon lit_ty [] [] [LitPat (mk_double lit) doublePrimTy]
 
-               -- Convert the literal pattern "" to the constructor pattern [].
-  | null_str_lit lit       = ConPat nilDataCon lit_ty [] [] [] 
-               -- Similar special case for "x"
-  | one_str_lit        lit        = ConPat consDataCon lit_ty [] [] 
-                               [mk_first_char_lit lit, ConPat nilDataCon lit_ty [] [] []]
+               -- Convert literal patterns like "foo" to 'f':'o':'o':[]
+  | str_lit lit           = mk_list lit
 
   | otherwise = default_pat
 
@@ -121,9 +118,14 @@ tidyLitPat lit lit_ty default_pat
     null_str_lit (HsString s) = _NULL_ s
     null_str_lit other_lit    = False
 
-    one_str_lit (HsString s) = _LENGTH_ s == (1::Int)
-    one_str_lit other_lit    = False
-    mk_first_char_lit (HsString s) = ConPat charDataCon charTy [] [] [LitPat (HsCharPrim (_HEAD_ s)) charPrimTy]
+    str_lit (HsString s)     = True
+    str_lit _                = False
+
+    mk_list (HsString s)     = foldr
+       (\c pat -> ConPat consDataCon lit_ty [] [] [mk_char_lit c,pat])
+       (ConPat nilDataCon lit_ty [] [] []) (_UNPK_ s)
+
+    mk_char_lit c            = ConPat charDataCon charTy [] [] [LitPat (HsCharPrim c) charPrimTy]
 \end{code}