testsuite/tests/ghci/scripts/T10963.script


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:type mapM
:type +d mapM
:t +d length
let foo :: (Num a, Monoid a) => a -> a; foo = undefined
:t +d foo
import Data.Semigroup
instance Semigroup Double where (<>) = (+)
instance Monoid Double where mempty = 0
:t +d foo