:type hangs on coerce
This works
$ ghci -ignore-dot-ghci
GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help
Prelude> import Data.Coerce
Prelude Data.Coerce> :t [fmap, coerce]
<interactive>:1:8: error:
• Occurs check: cannot construct the infinite type: b ~ f b
arising from a use of ‘coerce’
• In the expression: coerce
In the expression: [fmap, coerce]
But doing it with contra
Prelude Data.Coerce> contra = undefined :: Functor f => (b -> a) -> (f a -> f b)
it hangs
Prelude Data.Coerce> :t [coerce, contra]
^CInterrupted.
Prelude Data.Coerce> :t [contra, coerce]
^CInterrupted.