A readable version of the foreign async-problem

foreign.js

var fs = require('fs'),
    path = require('path'),
    foreign = require('foreign');

function readFile(filename, callback){
    fs.readFile(filename, {encoding: 'utf8'}, callback);
}

function complete(error, files){
    if(error){
        process.stderr.write(error.message + '\n');
    }else{
        process.stdout.write(files.join(''));
    }
    process.exit(error ? 1 : 0);
}

function relative(filename){
    return path.join(process.argv[2], filename);
}

function main(){
    readFile(relative('index.txt'), function(error, index){
        if(error) {
            return complete(error);
        }

        foreign.parallel(readFile, index.match(/^.*(?=\n)/gm).map(relative), complete);
    });
}

if (process.argv[1] === __filename) main();