[Haskell-beginners] IO Control Structures

[Francesco Ariis]

Hello Leonhard,

On Tue, Apr 23, 2019 at 02:55:22PM +0000, Leonhard Applis wrote:
> I don`t know how to do my main :: IO ()
> which should welcome the player, start the gameloop, and print godbyes the game if it's either won or lost
> Here i am missing a control structure, to demonstrate:
> 
> show hello
> board = initialBoard
> while (not end board)
>     board = gameLoop board
> show winner
> 
> I could also make my Gameloop recursive, while i think that i get this working, it seems awfully complex (and ugly) to me.

Indeed making gameLoop recursive is the (a) solution.
As now `gameLoop` isn't much of a loop, is it?
If gameLoop has a signature like this:

    gameLoop :: GameState ->                -- Initial State
                (IO Move) ->                -- Input function
                (State -> Move -> State) -> -- Logic function
                (State -> IO ()) ->         -- Blit function
                (State -> Bool)  ->         -- "Should I quit?" function
                IO ()

then main is trivial to write:

    main = do
        show hello
        board = initialBoard
        gameLoop board someInputFun makeMove drawState isOver
        show ciao