#6117: Cyclic Type Class Hierarchy Produces <<loop>>
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Reporter: jun0 | Owner: simonpj
Type: bug | Status: new
Priority: normal | Milestone: 7.8.1
Component: Compiler (Type checker) | Version: 7.4.1
Keywords: | Os: Linux
Architecture: Unknown/Multiple | Failure: Incorrect result at
runtime
Difficulty: Unknown | Testcase: T6117
Blockedby: | Blocking:
Related: |
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Comment(by simonpj):
You should not worry about this. In GHC we have kind `*` and kind
`Constraint`. They are really the ''same'' kind, so far as System FC is
concerned. But they are distinct in the following sense: given a type
{{{
f :: t1 -> t2 -> t3
}}}
where
{{{
t1 :: Constraint
t2 :: *
t3 :: *
}}}
the type inference engine will auto-instantiate a constraint for `t1`, but
not for `t2`. Also it'll display the type as
{{{
f :: t1 => t2 -> t3
}}}
What I need to so is to make the distinctions in only the right places,
and it's not quite right now.
In short, don't lose sleep.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6117#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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