The Problem with F# Evangelism

F# is way too entwined with .NET to be immediately useful to programmers familiar with Ocaml or Scala or Haskell, etc.

Some of the basic List., Array. stuff is simple enough, but then you start talking about interfaces and classes and members and all this stuff that doesn't really translate from C#->sanity very well.

I know people love it, but I've long considered C#/Java to be kludge languages on platforms they don't deserve. The JVM might be the most impressive software engineering marvel I can think of, and yet on top of that christmas tree stands a tall, stinky shit.

I'd love to see F# as a F#-first platform, and offer .NET interop as a secondary language feature.

I've also noticed a concerning trend in F# circles that """diversity""" should be celebrated. There is no merit in your skin color or your genitals. If you can hack well, you deserve to do so. End of story.

A counterpoint to the F# being poisoned by .NET is Clojure. Look how well Clojure did Java interop and how "not a big deal it is." Immutability everywhere, functional by default, and it feels painful to do things the Java way in Clojure. F# doesn't mind at all if you sink to .NET trickery and in some cases require it.

I could think of more, but off the top of my head, the .split instance method comes to mind. I have a Markov Chain kata that I spring on new hires to see how they do things, and .split is an instance method, which is counter-intuitive to how functional problems are solved because you don't just |> into it.

I'm waiting to see where Clojure goes with core.type before I abandon F#. I really WANT to keep riding the F# train but it causes quite a few headaches. Not more than it solves, but more than other solutions that I've considered.

To balance this out, I'll say something I really love about F#. Units of measure. Few languages have this, and the kind of numerical work we do means we really get our mileage out of UoM. I always see finance horror stories or like the excel rounding bug, it makes me wonder exactly how much money UoM has saved us from losing through some innocent type somewhere. Debugging money code is way easier when you can verify all the conversions separately from the logic. It feels like cheating, to be totally honest. I know there are big shops out there that don't have UoM in their tools, and I used to feel bad for them, but now that we have it, I can't help but NOT feel bad for them.

Anyways, yeah, F# isn't perfect. There's plenty to be said also for the amount of progress they make with language updates. It grows a crazy amount between major versions, and I haven't had too much problems yet taking old F#3.0 code and revitalizing it. Very pleasant experience in that regard as well.

For many programmers, the axioms of what a function are (a calling point to code which is contravariant in a product and covaraint in a single return value), what objects are (a unique closure over functions values with a syntactically supported lookup of named values and a system-provided identity function) are so unvarying in their experience as to be synonymous with the word we use to describe it without needing further quantification. That gets tricky when you want to say, "Ah, but this unique way of thinking about this datatype lets us pretend it's a function and then we need to talk about what it needs and what it provides in more general terms."

Since functional programming is actually all about completely tearing down the world to everything but a series of functions, it's unsurprising it needs different words.

Finding a way to entice users to join in the functional party is really difficult because asking a programmer to do it is roughly akin to asking them to learn to program again. And don't get me wrong, I think you emerge from the other side of it better and more productive in every way, but it's difficult to prove that and more difficult still to convince people of it.

Programmers learn how to program with C-style languages. C, C++, Java, C#, JavaScript, Python (sorta) . . . they're all in the same family. People, especially while learning, associate programming with specific constructs and idioms of C-style languages. It's incredibly difficult to break that barrier.

I think that functional programming is on the rise, and that more and more developers are starting to realize that the types of bugs that hold them back can be reduced by using a more powerful language. But it's got a very long way to go, because there is a lot of unlearning to do. The article alludes to this a bit. For example, immutability is one of the key concepts in nearly every FP language. Functional programmers take it for granted, but it's transformational and completely changes the way you have to solve a problem. This hump is often too big for many people to get over, at least in their first trial with a functional programming language. It's hard to solve a task you know how to solve when you now need to re-think your approach because the language doesn't let you change x in-place.

Additionally, I believe that many programmers aren't necessarily aware of all of the problems they're having. The next time you hear someone say, "and make sure to check for null here", watch them to see if they're seeing that as a general problem hurting their ability to get bits out the door or not. In my experience, it's not usually viewed that way. Yes, null is a necessary evil in many environments, but it's one that can be tamed, and different languages have already figured out how to do that. But unless it's seen as a problem by people at large, they won't see that as a carrot when you wave things like Optional types in front of them.

Overall, I'm still excited. Jet.com is a billion-dollar company that built their stuff with F#. There are similar stories of companies successful with F# (and other functional programming languages), and it feels as though this is happening more often. And as the mainstream (read: C-style languages) adopt more functional programming techniques, I think this will only get better. I think that people will see the value, then see a language which does it better, and give it a try.

They're eager to use the latest enhancements to C# that come from the functional world (e.g. lambdas, await/async), but it's impossible to get them to give up their mutable variables and null pointers.