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T19752.hs:12:10: error:
• Could not deduce (F b0 ~ a)
from the context: F b ~ a
bound by the type signature for:
f :: forall b. (F b ~ a) => a
at T19752.hs:12:10-23
Expected: forall b. (F b ~ a) => a
Actual: forall b. (F b ~ a) => a
‘a’ is a rigid type variable bound by
the type signature for:
g :: forall a. a
at T19752.hs:9:1-16
• In the ambiguity check for ‘f’
To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
In the type signature: f :: (F b ~ a) => a
In an equation for ‘g’:
g = f
where
f :: (F b ~ a) => a
f = undefined
• Relevant bindings include g :: a (bound at T19752.hs:10:1)
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