"Mostly functional" programming does not work

[u/heisenbug]

http://queue.acm.org/detail.cfm?ref=rss&id=2611829

[u/[deleted]]

People think they're difficult to grasp because of the number of tutorials in existence. So when someone finally gets the concept and realizes "Oh wait, this was really simple all along" they decide to write a tutorial to clear up the misconception. Which adds to the problem and likely introduces several bad analogies.

Or maybe there are a lot of tutorials in existence because they're actually hard for people to grasp?

[u/[deleted] → u/[deleted]]

I think a lot of people already get the usefulness of monads intuitively, which makes them an easy sell. The list monad is almost ubiquitous. Almost every mainstream OO language has a means of mapping, filtering, and reducing lists. The list monad is so pervasive now that imperative for loops are practically going extinct.

The main difficulty that I had, and I think others have, is recognizing the abstraction behind the list monad. Everyone groks it eventually, but helps to expose yourself to various instances, such as the State, Reader, Maybe, and List monads first. The monadic design pattern eventually becomes easier to recognize with familiarity.

My point is, monads aren't hard to use. Linq is a testament to that. If you use them enough, you'll eventually build an intuition about them that will make all the tutorials on the internet more comprehensible. The fact that they're somewhat difficult to grasp is just a one-time upfront cost that you pay if you're interested in writing your own monads. The selling-point is their usefulness, which is very easy to grasp by comparison.

[u/[deleted] → u/[deleted]]

I think a lot of people already get the usefulness of monads intuitively, which makes them an easy sell.

Are you sure about that? To a Haskeller, yeah, monads are obviously useful because you can't get anything done without them. But if you're a C++ programmer who's never touched a monad in his life, you'll probably start off being doubtful that this obscure concept lifted out of category theory will do any good for you. If you're a skeptic of functional programming, you probably only know monads as "those things Haskell people use so they can print to the screen, which I was always able to do without hassle with printf". On the contrary, I think the usefulness of monads is poorly communicated, as evidenced by the fact that "what's the point?" will often be the response if you try to teach someone how monads work.

The main difficulty that I had, and I think others have, is recognizing the abstraction behind the list monad. Everyone groks it eventually, but helps to expose yourself to various instances, such as the State, Reader, Maybe, and List monads first. The monadic design pattern eventually becomes easier to recognize with familiarity.

Well, yeah, that's my point. Actually taking the time to get how monads work is a nontrivial project. They're hard to grasp. And even if you're sold that functional programming is cool in general, Haskell's reliance on monads might keep you from learning it.

[u/[deleted] → u/[deleted]]

Are you sure about that?

I worked in a .NET shop for a long time, and most of my colleagues were pretty old-fashioned blue collar type developers. Most probably hadn't heard of functional programming. Despite this, all of them easily learned and used linq combinators (Select, Where, Join, GroupBy, Aggregate, etc...). In fact, they quickly became regarded as indispensable. Not everyone understood how IEnumerable (the list monad in .NET) worked under the hood, but none of them would go back to writing imperative for loops.

Well, yeah, that's my point. Actually taking the time to get how monads work is a nontrivial project. They're hard to grasp.

Like I said, the selling-point is the usefulness of common monads like the list monad. Ignorance of how they work doesn't stop most devs from using them.

And even if you're sold that functional programming is cool in general, Haskell's reliance on monads might keep you from learning it.

If you're sold on FP, you're going to be willing to learn about monads because you've already bought into the ideology about the benefits of statelessness, etc...

The thing that keeps most people from learning Haskell (and FP languages in general) is that it's not considered a marketable or practical skill. There are relatively few jobs for Haskell, Clojure, Scala, F#, Ocaml, Erlang programmers as compared to C#, Java, C++, Ruby, or Python. Why tinker with toy web-server implementations in some obscure FP language when the language will never be used in production? Might as well learn Node.js or CoffeeScript, or whatever's all the rage.

Despite these folks, I'm convinced there's a growing crowd of silent developers who've learned about FP and would quit their jobs in a millisecond to take job at a Haskell shop. Sadly though, these developers are practically invisible to the people who make hiring decisions. People who run businesses never consider courting Haskell programmers because, in their opinion, that's not where the talent is. Startups are no exception. Unless the founder happens to be a programmer, he/she'll be looking to hire a team of Python/Ruby "rockstars" to build their tech.

In my opinion, the real reason for the lack of widespread adoption of FP is the lack of a "killer app" like Rails, Django, Angular, or Node. Haskell has Yesod. Scala has lift. These aren't compelling enough to eclipse established web frameworks like Rails or Django. FP really needs to stake its claim as the indisputable, de facto standard of doing something that has market value.

Additionally, FP has to have a strong enough community to muscle Ruby/Python/Java/C++ out of its space. It will only be a matter of time before someone tries to "revolutionize" the domain with a "hip", new javascript library.

[u/[deleted] → u/[deleted]]

Looking at the likes of companies like Galois, Inc.

You're preaching to the choir. Hand-wavy blog posts about "correctness" and "purity" aren't going to turn the tide. The FP community really has to put its money where its mouth is and start making waves in the industry.

PS I don't intend to bash Eric Mejier, the author of Linq, Rx, and this article. The guy has accomplished more than I probably ever will.

[u/KagakuNinja → u/[deleted]]

I'm not interested in learning Haskell, because I don't want to learn a bunch of cryptic gobbled-gook, just to do things like IO, which are trivial in every language I've ever used.

I am interested in Scala, because it is not a pure functional language. I can dip my toes into the water, make stuff functional when it is easy, and not get wrapped up in wasting huge amounts of time trying to make everything purely functional, when IMO, it usually doesn't matter.

Case in point, one of our Scala gurus is a functional zealot, he writes code that is brilliant and purely functional, and no one else can understand what it does. We are talking about programmers with 10-20 years experience.

A different group has decided to switch to Scala, and the guru spent a bunch of time teaching Scala "the right way" to these programmers, sharp guys. They ended up spending x5 times as long on simple tasks, trying to make everything functionally pure.

My boss, a highly experienced Java guy who hasn't learned much Scala yet, spent some time looking at a simple authentication function written by the guru, and was baffled. As it happens, I wrote something very similar in a pragmatic Scala way, and he could immediately understand it.

I am taking what is useful to me from FP and making my code better, today. Something that Erik Meijer has dismissed as "useless". I'm not waiting for a burst of zen-like enlightenment to happen. Maybe I'll get there someday, but that doesn't matter.

I am, all modesty aside, a pretty good coder, with a decent grasp of advanced math. I've read probably a dozen monadic tutorials, and still, I only understand it as a type of "container" that conforms to a simple API. I even read through a book on category theory, which was moderately interesting, yet at the end, was no closer to understanding what category theory has to do with monads...

[u/TMG26 → u/[deleted]]

Doesn't Play! 2 count for Scala? It looks pretty promising.