#65: depth cutoff reports the wrong constraint
-------------------------+--------------------------------------------------
Reporter: ross | Owner: nobody
Type: defect | Status: new
Priority: major | Milestone:
Component: type system | Version: 200609
Keywords: |
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Given the following:
{{{
class C a where
f :: a -> a
instance (Eq a, C a) => C a
test = f True
}}}
hugs -98 reports
{{{
ERROR "Silly.hs" -
*** The type checker has reached the cutoff limit while trying to
*** determine whether:
*** Eq Bool
*** can be deduced from:
*** ()
*** This may indicate that the problem is undecidable. However,
*** you may still try to increase the cutoff limit using the -c
*** option and then try again. (The current setting is -c40)
}}}
when in fact it is trying to solve `C Bool`.
--
Ticket URL: <
http://hackage.haskell.org/trac/hugs/ticket/65>
Hugs <
http://www.haskell.org/hugs/>
Hugs 98, an interpreter for Haskell
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