#3850: EmptyDataDecls and type context
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Reporter: Paczesiowa | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.1
Keywords: emptydatadecls | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: GHC rejects valid program
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Comment(by simonpj):
What makes you think that GHC will reject the type `(Label Bool Foo Foo)`?
I don't think it will.
The only effect of a context on a data decl is that a use of the
constructor, either in pattern matching or in an expression, gives rise to
that constraint. That's all.
So the constraint is no more than a comment. I suggest you use a comment!
I'm really want a proper kind system, though. It's silly that we can't
give the kind of Label. But contexts are not the way to do it.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3850#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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