#7332: Kind-defaulting omitted leads to deeply obscure type error
---------------------------------+------------------------------------------
Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: high | Milestone: 7.8.1
Component: Compiler | Version: 7.6.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
---------------------------------+------------------------------------------
Changes (by simonpj):
* priority: normal => high
* milestone: => 7.8.1
Comment:
Good catch! In the transition from 7.4 I simplified the way that let-
generalised types are inferred, and in so doing introduced an error. In
this case it's because we infer a constraint `Build (DC d) (a -> t)`,
where `a :: OpenKind`.... and that means it doesn't match the instance
declaration. However it is defaulted to `a : *` during quantification,
and the result is very confusing and wrong.
Happily it's easy to fix. Patch coming.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7332#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
