> You need a PhD in type theory to get anywhere.
That is extremely false. Haskell isn't even a good playground for academic type theory -- you'd want Agda etc. for that. The development of the language over the last few years has been characterized by pragmatism and a focus on backwards-compatibility, which is why you can take code from something like ten years ago and have it run without issues on modern versions of the Haskell compiler with little to no modifications. (Let's not talk about how long code written in "modern" JS lasts.)
And I'd really like to see type class constraint resolution with functional dependencies, or Hindley-Milner type checking, or something of that sort implemented in "5-10 lines" of JS.
"There he goes again with his mumbo-jumbo," you say. That's right, you don't need to care about those things to write Haskell. What you meant is implementations of typeclasses ("interfaces") like Monad, Functor, and so on: they don't take much more code in Haskell.
Array.prototype.chain = function (f) {
return this.reduce((acc, it) => acc.concat(f(it)), [])
}
instance Monad [] where
xs >>= f = concat (map f xs)
return = pure
And we didn't even have to go the "this" route! Notice that your 5 - 10 lines of JS don't let you write code that works in any monad, whereas I can easily write
whenM :: Monad m => m Bool -> m () -> m ()
whenM cond action = do
condition
In Elm, you'd have List.whenM, Array.whenM, Maybe.whenM, ... or a straight-up false type signature like their Eq ones, and in JS, a bunch of prototype methods with no unifying threads.
--
As for an example of why I think Haskell has the right ideas (few of us will say it's the "best language evar"):
I'd really like to see a JS version of the Servant library, which takes an API spec for a server and actually generates a fully functional server from that. Here's a description:
https://news.ycombinator.com/item?id=14149200
Does this strike you as idle theoretical self-enjoyment?