Main.purs

module Main where

import Control.Monad.Eff

import Data.Either
import Data.Foreign
import Data.Function

import Debug.Trace

type ErrorCode = String
type FilePath  = String

type M eff = Eff (fs :: FS | eff)

foreign import data FS :: !

foreign import readFileImpl
"""
function readFileImpl (path, onSuccess, onFailure) {
  return function () {
    require ('fs').readFile (path,
            { encoding: 'utf-8' },
            function (error, data) {
              if (error) {
                onFailure (error.code);
              }
              else {
                onSuccess (data);
              }
            });
  };
};
""" :: forall eff. Fn3 FilePath
                       (String    -> M eff Unit)
                       (ErrorCode -> M eff Unit)
                       (M eff Unit)

readFile :: forall eff. FilePath ->
                        (Either ErrorCode String -> M eff Unit) ->
                        M eff Unit
readFile path cb = runFn3 readFileImpl path (cb <<< Right) (cb <<< Left)

main = readFile "/tmp/1.txt" print