patch applied (ghc): Fix Trac #4917: try a bit harder to unify on-the-fly
Simon Peyton Jones
simonpj at microsoft.com
Tue Jan 25 12:06:11 CET 2011
Tue Jan 25 03:01:12 PST 2011 simonpj at microsoft.com
* Fix Trac #4917: try a bit harder to unify on-the-fly
This is generally a modest improvement but, more important,
it fixes a "unify-under-forall" problem. See Note [Avoid deferring].
There's still a lurking unsatisfactory-ness in that we can't
defer arbitrary constraints that are trapped under a forall.
M ./compiler/typecheck/TcUnify.lhs -8 +28
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