> “If functional programming is so great, why is it still niche? We have a product that can practically eliminate runtime errors, make refactoring much easier, lighten the testing burden, all while being quite delightful to use. What’s the hold up?”

I think they are over-estimating how much people care about runtime errors.

I agree. I've worked in both Elm and ClojureScript. In one, I have to constantly deal with compiler errors. In the other, about as much runtime errors. The net time for error handling is the same. But the net time in actually writing code is in favor of ClojureScript, which requires at least half as many lines as Elm (and often much less than half).

Error handling is somewhat over-emphasized in comparison to other things that affect productivity (and maintainability).

Especially on the JVM where most exceptions need to be explicitly handled and the ones that aren't can be handled in a way that doesn't impact users.

elm-lang is a front-end only language compiled to JS(at the moment).

JVM doesn’t apply hence.

> “If functional programming is so great, why is it still niche?

It's niche because learning a language is the exact opposite of fast iterative process with immediate feedback. The feedback cycle of learning and evaluating a language is 6th months to multiple years, which means it takes a lot to really evaluate one. Then the added issue of network effects (ie needing others to know the language in a team).

I am not sure it is niche anymore. Java 8 added many functional features to Java. :)

Functional 'concepts' are not niche, but functional languages still are. If you asked your average Java 8 programmer or JS programmer to write an app in Haskell or Elm, they'd struggle.

I'd consider myself an average JS programmer and would love to try writing web apps in Haskell. I've spent some time on Haskell books, fell in love with the type system, got a basic understanding of monads but found it difficult to "move forward".

I think the issue for me is I predominantly build web apps. Can you recommend any resources for building modern web apps in Haskell or at least fitting it into my day to day at work?

Try PureScript! [1]

Haskell-like (but taking away some of the pain points), for the frontend, compiles to very readable javascript.

[1]: http://www.purescript.org/

That looks really cool :) does it still depend on Bower?

There's no "dependency" per se, but in practice most of the community still uses bower.

There's an effort to make something better and on the same vibe as Haskell's `stack`, which is `psc-package` [1].

I switched to it for all new projects, and while it still has some rough edges, I don't really miss bower.

[1]: https://github.com/purescript/psc-package

Unfortunately, does not use persistent data structures.

Yes it does.

So did C++. But you can't program C++ or Java in a functional manner the way you can an actual FP language. Largely due to lack of proper data structures for FP.

why do we need Parinfer, why not dropping parentheses altogether in favour of itendantion

If I type () I have every reason to expect you'll see them, because nobody foolishly writes tools that mangle them.