#2893: Implement "Quantified contexts" proposal
---------------------------------+------------------------------------------
Reporter: porges | Owner:
Type: feature request | Status: new
Priority: normal | Milestone: _|_
Component: Compiler | Version: 6.10.1
Severity: normal | Resolution:
Keywords: proposal | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
---------------------------------+------------------------------------------
Comment (by porges):
A short version... we allow contexts of the form:
{{{
(forall a. Bar f a) => Foo f
}}}
And more generally, these contexts can have contexts of their own:
{{{
(forall a. (Baz a) => Bar f a) => Foo f
}}}
I'm not sure if the 'more general' version adds extra difficulty in type-
checking, as I am not very familiar with its intricacies.
Forgive my stupidity, I don't understand where the typechecking (at least
in the first) becomes so difficult—the context means that there is an
instance available which is free in the specified variable.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2893#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
