The below gist shows how to take care of global variables and also make funcs chainable

currying-example.js

//The below gist shows how to take care of global variables and also make funcs chainable

//Global indexURLs map for different languages
let indexURLs = {
    'en': 'http://mysite.com/en',  //English
    'sp': 'http://mysite.com/sp', //Spanish
    'jp': 'http://mysite.com/jp'   //Japanese
}

//Imperative
const getUrl = (language) => allUrls[language]; //Simple, but error prone and impure (accesses global variable)


//Functional Programming

//Before currying:
const getUrl = (allUrls, language) => {
    return Maybe(allUrls[language]);
}

//After currying:
const getUrl = R.curry(function(allUrls, language) {//curry to convert this to a single arg func
    return Maybe(allUrls[language]);
});

const maybeGetUrl = getUrl(indexURLs) //Store global value in the 'curried' function.

//From this point, maybeGetUrl needs only one argument(language). So we can now chain this like:
maybe(user).chain(maybeGetUrl).bla.bla