Mercurial > urweb
diff src/elab_err.sml @ 1742:fca4a6d05ac1
More diagnostic information about some type class resolution failures
author | Adam Chlipala <adam@chlipala.net> |
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date | Fri, 04 May 2012 10:33:04 -0400 |
parents | 0bafdfae2ac7 |
children | 818d4097e2ed |
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--- a/src/elab_err.sml Fri May 04 10:07:27 2012 -0400 +++ b/src/elab_err.sml Fri May 04 10:33:04 2012 -0400 @@ -239,17 +239,10 @@ ("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)(*, - ("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))*)]) + eprefaces' ([("Class constraint", p_con env c)] + @ (case E.resolveFailureCause () of + NONE => [] + | SOME c' => [("Reduced to unresolvable", p_con env c')]))) | IllegalRec (x, e) => (ErrorMsg.errorAt (#2 e) "Illegal 'val rec' righthand side (must be a function abstraction)"; eprefaces' [("Variable", PD.string x),