[Haskell-beginners] How to check the help page of a function?

[Peng Yu]

> GHCi has such a command:
>   :doc <function name>
>
> For example:
>   Prelude> :doc head
>   Prelude head :: [a] -> a
>
>   Extract the first element of a list, which must be non-empty.
>
>   From package base
>   head :: [a] -> a

Where is it? I don't see it.

GHCi, version 7.10.1: http://www.haskell.org/ghc/  :? for help
Prelude> :doc head
unknown command ':doc'
use :? for help.
Prelude>


-- 
Regards,
Peng