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diff src/elab_err.sml @ 711:7292bcb7c02d

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Made type class system very general; demo compiles
author Adam Chlipala <adamc@hcoop.net>
date Thu, 09 Apr 2009 12:31:56 -0400
parents 1fb318c17546
children 915ec60592d4
line wrap: on
line diff
--- a/src/elab_err.sml	Tue Apr 07 20:38:01 2009 -0400
+++ b/src/elab_err.sml	Thu Apr 09 12:31:56 2009 -0400
@@ -217,7 +217,17 @@
                                               ("Type", p_con env c)]) co)
       | Unresolvable (loc, c) =>
         (ErrorMsg.errorAt loc "Can't resolve type class instance";
-         eprefaces' [("Class constraint", p_con env c)])
+         eprefaces' [("Class constraint", p_con env c),
+                     ("Class database", p_list (fn (c, rules) =>
+                                                   box [P.p_con env c,
+                                                        PD.string ":",
+                                                        space,
+                                                        p_list (fn (c, e) =>
+                                                                   box [p_exp env e,
+                                                                        PD.string ":",
+                                                                        space,
+                                                                        P.p_con env c]) rules])
+                                        (E.listClasses env))])
       | IllegalRec (x, e) =>
         (ErrorMsg.errorAt (#2 e) "Illegal 'val rec' righthand side (must be a function abstraction)";
          eprefaces' [("Variable", PD.string x),