﻿id summary reporter owner description type status priority milestone component version resolution keywords cc os architecture failure difficulty testcase blockedby blocking related 1241 Functional dependency Coverage Condition is lifted, and should not be guest "Hello, GHC 6.6 (with flags {{{-fglasgow-exts -fallow-undecidable-instances}}}) is too liberal when accepting instances. Here is an example: {{{ class F a b | a -> b where f :: (a,b) instance F Int b }}} The instance violates the functional dependency constraint of {{{F}}} because (in theory) it can be used to solve both {{{F Int Bool}}} and {{{F Int Char}}}. In practice, it seems that some free variable gets bound upon the first use of {{{f}}} with a concrete type, leading to some rather confusing behavior. Example: {{{ x :: (Int,a) x = f y :: (Int,Bool) y = f z :: (Int,Char) z = x -- works, but 'z = f' does not }}} -Iavor" bug closed normal ⊥ Compiler (Type checker) 6.6 fixed sulzmann@… Unknown/Multiple Unknown/Multiple None/Unknown Unknown