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T1897b.hs:16:1: error: [GHC-83865]
• Couldn't match type: Depend a0
with: Depend a
Expected: t (Depend a) -> Bool
Actual: t (Depend a0) -> Bool
NB: ‘Depend’ is a non-injective type family
The type variable ‘a0’ is ambiguous
• In the ambiguity check for the inferred type for ‘isValid’
To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
When checking the inferred type
isValid :: forall {t :: * -> *} {a}.
(Foldable t, Bug a) =>
t (Depend a) -> Bool
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