#2356: GHC accepts multiple instances for the same type in different modules
----------------------+-----------------------------------------------------
Reporter: claus | Owner:
Type: bug | Status: new
Priority: low | Milestone: _|_
Component: Compiler | Version: 6.8.3
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Unknown
Os: Unknown |
----------------------+-----------------------------------------------------
Changes (by spl):
* cc: [EMAIL PROTECTED] (added)
* version: 6.8.2 => 6.8.3
Comment:
I prefer having GHC work as it does now. It makes sense to me that
instances only overlap when used and not just when imported. If GHC
changes, I would like the option to get back to the current approach, but
without requiring {{{-fallow-overlapping-instances}}}. Perhaps some
language extension. Also, has this been mentioned in haskell-prime?
I just recently learned about this issue first-hand. See the glasgow-
haskell-users thread starting
[http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/14970/focus=14992
here] with my own
[http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/14970/focus=14999
simple example] that highlights the usefulness of instances working the
way they do now.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2356#comment:7>
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
