[Haskell-beginners] Import issue

[Brandon Allbery]

On Fri, May 8, 2015 at 2:25 PM, Shishir Srivastava <
shishir.srivastava at gmail.com> wrote:

> I've imported the State monad module and used in the 'pop' function that
> will pop the head out of the list but am getting error in GHCi.
>

You are probably working from outdated documentation of some kind. The
original standalone monads like State from mtl1 were replaced several years
ago with type aliases (in this case `type State s a = StateT s Identity a`)
in mtl2, which means State is no longer a constructor. The `state` function
can be used as a quick replacement for the old `State` constructor for any
purpose other than pattern matching.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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