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T14172.hs:6:46: error:
• Found type wildcard ‘_’ standing for ‘a'’
Where: ‘a'’ is a rigid type variable bound by
the inferred type of
traverseCompose :: (a -> f b) -> g a -> f (h a')
at T14172.hs:7:1-46
To use the inferred type, enable PartialTypeSignatures
• In the first argument of ‘h’, namely ‘_’
In the first argument of ‘f’, namely ‘(h _)’
In the type ‘(a -> f b) -> g a -> f (h _)’
T14172.hs:7:19: error:
• Couldn't match type ‘a’ with ‘g'0 a’
Expected: (f'0 a -> f (f'0 b)) -> Compose f'0 g'0 a -> f (h a')
Actual: (Unwrapped (Compose f'0 g'0 a) -> f (Unwrapped (h a')))
-> Compose f'0 g'0 a -> f (h a')
• In the first argument of ‘(.)’, namely ‘_Wrapping Compose’
In the expression: _Wrapping Compose . traverse
In an equation for ‘traverseCompose’:
traverseCompose = _Wrapping Compose . traverse
• Relevant bindings include
traverseCompose :: (a -> f b) -> g a -> f (h a')
(bound at T14172.hs:7:1)
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