GHC panic (no skolem info)
The attached program causes GHC 7.10.2 to panic with the following output:
bug.hs:6:19:
Found hole ‘_’ with type: t1 → t2 → m1 a1 → m1 a1
Where: ‘t1’ is a rigid type variable bound by
the inferred type of
whenMultipleOf ∷ MonadPlus m1 ⇒ t1 → t2 → m1 a1 → m1 a1
at bug.hs:7:1
‘a1’ is a rigid type variable bound by
the inferred type of
whenMultipleOf ∷ MonadPlus m1 ⇒ t1 → t2 → m1 a1 → m1 a1
at bug.hs:7:1
‘m1’ is a rigid type variable bound by
the inferred type of
whenMultipleOf ∷ MonadPlus m1 ⇒ t1 → t2 → m1 a1 → m1 a1
at bug.hs:7:1
‘t2’ is a rigid type variable bound by
the inferred type of
whenMultipleOf ∷ MonadPlus m1 ⇒ t1 → t2 → m1 a1 → m1 a1
at bug.hs:7:1
To use the inferred type, enable PartialTypeSignatures
In the type signature for ‘whenMultipleOf’: _
bug.hs:7:1:
No instance for (MonadPlus m)
When checking that ‘whenMultipleOf’ has the specified type
whenMultipleOf ∷ ∀ t a (m ∷ * → *) t1. t → t1 → m a → m a
Probable cause: the inferred type is ambiguous
bug.hs:10:62:
Couldn't match type ‘a1’ with ‘t’
‘a1’ is a rigid type variable bound by
the type signature for
sumOfMultiples ∷ Integral a1 ⇒ [a1] → a1 → [a1]
at bug.hs:9:19ghci-ng: panic! (the 'impossible' happened)
(GHC version 7.10.2 for x86_64-unknown-linux):
No skolem info: t_a7vV[sk]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug