Command.hs

{-# Language DeriveFunctor #-}
module Command where

import Control.Monad (replicateM_)
import Control.Monad.Free

(|>) :: (Monad m) => Int -> m a -> m ()
(|>) = replicateM_

data CommandF a = MoveForward a | DestroyBlock a deriving (Functor)

type Command = Free CommandF ()

moveForward :: Command
moveForward = liftF $ MoveForward ()

destroyBlock :: Command
destroyBlock = liftF $ DestroyBlock ()

program = do
  2 |> do
    moveForward
  destroyBlock

display :: Command -> String
display (Free m@(MoveForward next)) = "moveForward()\n" ++ display next
display (Free d@(DestroyBlock next)) = "destroyBlock()\n" ++ display next
display (Pure ()) = ""

print' = putStrLn . display

Main.hs

module Main where

import Spell
import Player
import Foo

main :: IO ()
main = print' program

output.js

moveForward();
moveForward();
destroyBlock();