20 May
2004
20 May
'04
6:34 p.m.
that is not the case with "-fallow-undecidable-instances" ... as far as I understand it , ghc never considers the dependancies when selecting an instance. If you don't think so you will need to show me an example where it clearly does... as I haven't seen one yet (but just because I haven't seen it doesn't mean its not possible),,, IMHO, things should either stay as they are (only instance heads supported) or it should switch to full Prolog style backtracking. Given who I mean, given two instances like: instance a b c instance d e f there is no way to tell between them... if you said choose a in preferenc 'a' would be chosen all the time. Keean.