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-- !!! Ambiguity in local declarations
module ShouldSucceed where
type Cp a = a -> a -> Ordering
m :: Eq a => Cp a -> [a] -> a
m _ [x,y,z] = if x==y then x else z
cpPairs :: Cp [j] -> (a,[j]) -> (a,[j]) -> Ordering
cpPairs cp (_,p) (_,q) = cp p q
mp :: (Eq i,Eq j) => Cp [j] -> [(i,[j])] -> (i,[j])
mp cp dD =
let minInRow = m (cpPairs cp)
in minInRow dD
{- GHC 3.02 reported
T.hs:24:
Ambiguous type variable(s)
`j' in the constraint `Eq (aYD, [j])'
arising from use of `m' at T.hs:24
In an equation for function `mp':
mp cp dD = let minInRow = m (cpPairs cp) in minInRow dD
This was because the ambiguity test in tcSimplify didn't
take account of the type variables free in the environment.
It should compile fine.
-}
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