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T4093b.hs:31:13: error: [GHC-25897]
• Could not deduce ‘e ~ C’
from the context: (EitherCO e (A C O n) (A O O n) ~ A e O n,
EitherCO x (A C C n) (A C O n) ~ A C x n)
bound by the type signature for:
blockToNodeList :: forall (n :: * -> * -> *) e x.
(EitherCO e (A C O n) (A O O n) ~ A e O n,
EitherCO x (A C C n) (A C O n) ~ A C x n) =>
Block n e x -> A e x n
at T4093b.hs:(19,1)-(22,26)
Expected: EitherCO e (A C O n) (A O O n)
Actual: (MaybeC C (n C O), MaybeC O (n O C))
‘e’ is a rigid type variable bound by
the type signature for:
blockToNodeList :: forall (n :: * -> * -> *) e x.
(EitherCO e (A C O n) (A O O n) ~ A e O n,
EitherCO x (A C C n) (A C O n) ~ A C x n) =>
Block n e x -> A e x n
at T4093b.hs:(19,1)-(22,26)
• In the expression: (JustC n, NothingC)
In an equation for ‘f’: f n _ = (JustC n, NothingC)
In an equation for ‘blockToNodeList’:
blockToNodeList b
= foldBlockNodesF (f, l) b z
where
z ::
EitherCO e (EitherCO e (A C O n) (A O O n)) (EitherCO e (A C O n) (A O O n))
z = undefined
f ::
n C O
-> EitherCO e (A C O n) (A O O n) -> EitherCO e (A C O n) (A O O n)
f n _ = (JustC n, NothingC)
....
• Relevant bindings include
f :: n C O
-> EitherCO e (A C O n) (A O O n) -> EitherCO e (A C O n) (A O O n)
(bound at T4093b.hs:31:5)
l :: n O C
-> EitherCO e (A C O n) (A O O n) -> EitherCO e (A C C n) (A O C n)
(bound at T4093b.hs:34:5)
b :: Block n e x (bound at T4093b.hs:25:17)
blockToNodeList :: Block n e x -> A e x n (bound at T4093b.hs:25:1)
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