You can use the :t
command in ghci
to find out the type of any expression.
GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help
Prelude> :t flip foldr id
flip foldr id
:: Foldable t => (a -> (a1 -> a1) -> a1 -> a1) -> t a -> a1 -> a1
solved Get the type of `flip foldr id` in Haskell from the console