InfoQ
9 HN recommenders · recommended in 9 months, 2014–2022
36:31 · 141K views · May 21, 2013
Brian Lonsdorf explains why Underscore.js falls short as a functional programming library, then introduces currying, composition and point-free style in JavaScript. He argues for data-last argument ordering.
A repeatedly recommended introduction to functional JavaScript that explains currying and why data should come last.
12 comments from Hacker News
That is great feedback. I am actually working on creating a "functional" version of the 2048 game, along with my own implementation of the AI solver, as part of this series. Kinda goofy, and maybe not a "real world" situation as much, but should at least show the concepts being applied. I also very much recommend this video by Brian Lonsdorf, titled "Hey Underscore, You're Doing It Wrong!: this video
There is an excellent talk called "Underscore, you're doing it wrong!". The talk explains how well designed param order with currying leads to very short and expressive code -- and how underscore missed the boat. This aspect of it should be interesting as it's related to this post. It's well worth the watch. this video
I find this talk inspiring. Underscore.js got many things wrong for FP: this video . I've read Grokking Simplicity too. It's very approachable book. Highly recommend it for JS/TS developers who want to learn FP!
You might already be using certain functional programming constructs without being aware of them. Contrary to popular misconception, OOP and functional programming don't have to be mutually exclusive. "Pure" functional programming (ala Haskell) and OOP most certainly are to an extent non-overlapping (since OOP has state+behaviour at its core), and pure fn-languages have no side-effects. High-order function in java don't exist, so one would do : new Thread(new Runnable() { ... }).start(); A builder pattern can be distilled down as a form of partial application (or, currying, if you like. They aren't the same thing, but are very similar): alertDialog .setMessage(...) .setPositiveButtonText(...) .setNegativeButtonText(...) .setPositiveButtonOnClickListener(...) .setNegativeButtonOnClickListener(...) .build() .show() Functors (in OCaml) can be viewed as Java's abstract-generic-classes with dependency injection [0]. Note that functors in different languages mean different things. Monads are tricky to understand [1], I have been led to believe. But if you use the promises API in javascript, then you're using a form of monad [2]. If you're familiar with javascript, have a look at: this video (Hey Underscore, you're doing it wrong!) I think the best way is to read a book on fn-programming. I've heard most people recommend these (pick a language, and choose a book; you cannot go wrong with any of these): Functional DS: [LINK] Real World Haskell: [LINK] Real World OCaml: [LINK] The Joy of
With all due respect, I don't think you understand the purpose of currying and partial application. In your defense, the article merely explains what currying is, but does not explain why you need it. For instance while writing functional Javascript code, I never curry my methods, instead I use helper methods from functional libraries such as lodash or Ramda to curry. Where currying is useful is in cases like this: ```javascript //Definitions const filterUsers = (fieldName, value, users) => //Implementation const sortUsersBy = (fieldName, users) => //Implementation const takeUsers = (count, users) => //Implementation //Without currying UserService .getUsers() .then(users => filterUsers('active', true, users)) .then(users => sortUsersBy('age', users)) .then(users => takeUsers(3, users)); //If these methods were curried UserService .getUsers() .then(filterUsers('active', true)) .then(sortUsersBy('age')) .then(takeUsers(3)); ``` Here is a video which explains proper uses of currying (and does it very well) [1]. Here is another article if your coworker start using functional programming and you want to stop them [2]. 1. this video 2. [LINK]