# HG changeset patch
# User haftmann
# Date 1260782644 -3600
# Node ID 420234017d39640da983f0e66055373b1ebd48db
# Parent  05cb31ca48ae7aaa8d931582661175eaa217c77b
improved crude deriving_show inference

diff -r 05cb31ca48ae -r 420234017d39 src/Tools/Code/code_haskell.ML
--- a/src/Tools/Code/code_haskell.ML	Mon Dec 14 10:23:25 2009 +0100
+++ b/src/Tools/Code/code_haskell.ML	Mon Dec 14 10:24:04 2009 +0100
@@ -330,11 +330,12 @@
     fun deriving_show tyco =
       let
         fun deriv _ "fun" = false
-          | deriv tycos tyco = member (op =) tycos tyco orelse
-              case try (Graph.get_node program) tyco
+          | deriv tycos tyco = not (tyco = Code_Thingol.fun_tyco)
+              andalso (member (op =) tycos tyco
+              orelse case try (Graph.get_node program) tyco
                 of SOME (Code_Thingol.Datatype (_, (_, cs))) => forall (deriv' (tyco :: tycos))
                     (maps snd cs)
-                 | NONE => true
+                 | NONE => true)
         and deriv' tycos (tyco `%% tys) = deriv tycos tyco
               andalso forall (deriv' tycos) tys
           | deriv' _ (ITyVar _) = true