#3485: "Illegal type synonym family application in instance" error is
unnecessary,
should be removed
-------------------------------------+--------------------------------------
Reporter: Ashley Yakeley | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.10.4
Severity: normal | Resolution: invalid
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
-------------------------------------+--------------------------------------
Changes (by chak):
* status: new => closed
* resolution: => invalid
Comment:
I am not sure what you are suggesting. We cannot automatically transform
{{{
instance C (Fam Int)
}}}
into
{{{
instance (Fam Int ~ famint) => C famint
}}}
This works if there is only one instance, but as soon as there are two
such instances, they always overlap.
Maybe you are suggesting that we should do it anyway and programmers
should just take the implicit transformation into account. I don't think
that this is a good idea. It's confusing for very little benefit (as you
can always write the transformed instance yourself with little effort).
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3485#comment:1>
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
