[GHC] #12923: MultiParamTypeClasses + ExtendedDefaultRules
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Sat Dec 10 00:07:45 UTC 2016
#12923: MultiParamTypeClasses + ExtendedDefaultRules
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Reporter: amindfv | Owner:
Type: feature request | Status: patch
Priority: normal | Milestone: 8.2.1
Component: Compiler | Version: 8.0.1
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s): Phab:D2816
Wiki Page: |
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Comment (by simonpj):
I don't think that rule will work. As the user manual page says, the list
type `[] :: * -> *` is in the list of type defaults, so that higher-kinded
variables can be defaulted too. See #10971.
So we can't restrict to *.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12923#comment:6>
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