Notes for Johan Lindberg

gistfile1.lhs

In http://github.com/johanlindberg/langgeeks/commit/3e6249fcd36be6685cce2a6936da8dd2471cbd51 
you have:

> process :: String -> (Char, [String])
> process filename = do contents <- readFile filename
>                      return (getPlayer contents, getBoard contents)

It looks like you want to read the file and extract the player and board to pass this on to 
another function. All that is missing here is the IO in the type signature.

> process :: String -> IO (Char, [String])
> process filename = do contents <- readFile filename
>                       return (getPlayer contents, getBoard contents)

Then you could write findAllMoves as:

> findAllMoves :: String -> IO ()
> findAllMoves filename = do (player, board) <- process filename
>                            print (findMoves player board)

Both of these have to be "in IO" because they both do some IO.

Alternatively, you could factor it differently, separating the pure from the IO code:

> findAllMoves :: String -> [(Int, Int)]
> findAllMoves contents = findMoves (getPlayer contents) (getBoard contents)

> process :: String -> IO ()
> process filename = do contents <- readFile filename
>                       print (findAllMoves contents)

Or keep it all together being clear about the sub expressions:

> findAllMoves :: String -> IO ()
> findAllMoves filename = do contents <- readFile filename
>                            let player = getPlayer contents
>                            let board  = getBoard  contents
>                            let moves  = findMoves player board
>                            print moves

I'm not sure which I like best. Your solution is perfectly fine, but I'm sensing you were 
frustrated that you couldn't separate it out the way you wanted to.