papa.eric@free.fr escribió:
Hi haskell helpers,
Learning haskell, I wanted to explore how to write pure code and then add some IO on top of it, keeping the main code pure. The idea was to write a very simple two-player game, then define some strategies to play it that do not involve IO, and finally use strategies involving Random or IO ("ask the user"). I failed to reuse the pure code, and the only solution I found was to rewrite most things for IO. Here is my attempt in literate haskell, it is quite short, I hope someone will be kind enough to tell me what I have missed... Thanks for any answer! I know mainly two options, the first is using unsafe IO which is a small heresy.
The other is using the Control.Monad lift function which will apply pure functions over IO ones returning an IOized type. Ie if we have an b :: IO Int b = return 3 and we do c = lift (+ 2) b We will get IO(5) when we use c