diff -r 8752ca7f849a -r 997cef733bdd src/HOL/Library/Pretty_Int.thy
--- a/src/HOL/Library/Pretty_Int.thy	Sun May 13 18:15:23 2007 +0200
+++ b/src/HOL/Library/Pretty_Int.thy	Sun May 13 18:15:24 2007 +0200
@@ -20,6 +20,9 @@
   (OCaml "Big'_int.big'_int")
   (Haskell "Integer")
 
+code_instance int :: eq
+  (Haskell -)
+
 setup {*
   fold (fn target => CodegenSerializer.add_pretty_numeral target
     (@{const_name number_of}, @{typ "int \<Rightarrow> int"})