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T3169.hs:13:22:
Could not deduce (Map a ~ MP a b)
from the context (Key a, Key b)
bound by the instance declaration at T3169.hs:10:10-36
Expected type: Map a (Map b elt)
Actual type: Map (a, b) elt
Relevant bindings include
lookup :: (a, b) -> Map (a, b) elt -> Maybe elt
(bound at T3169.hs:12:3)
a :: a (bound at T3169.hs:12:11)
b :: b (bound at T3169.hs:12:13)
m :: Map (a, b) elt (bound at T3169.hs:12:17)
In the second argument of `lookup', namely `m'
In the expression: lookup a m :: Maybe (Map b elt)
In the expression:
case lookup a m :: Maybe (Map b elt) of {
Just (m2 :: Map b elt) -> lookup b m2 :: Maybe elt }
T3169.hs:13:22:
Could not deduce (elt ~ Map b elt)
from the context (Key a, Key b)
bound by the instance declaration at T3169.hs:10:10-36
`elt' is a rigid type variable bound by
the type signature for
lookup :: (a, b) -> Map (a, b) elt -> Maybe elt
at T3169.hs:12:3
Expected type: Map a (Map b elt)
Actual type: Map (a, b) elt
Relevant bindings include
lookup :: (a, b) -> Map (a, b) elt -> Maybe elt
(bound at T3169.hs:12:3)
b :: b (bound at T3169.hs:12:13)
m :: Map (a, b) elt (bound at T3169.hs:12:17)
In the second argument of `lookup', namely `m'
In the expression: lookup a m :: Maybe (Map b elt)
In the expression:
case lookup a m :: Maybe (Map b elt) of {
Just (m2 :: Map b elt) -> lookup b m2 :: Maybe elt }
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