> It comes down to trust. You're either fucking with your code in a powerful programming language that lets you do everything, or your fucking with the language restrictions to get your code to compile in the first place.

> ...or your fucking with the language restrictions to get your code to compile in the first place

I think that's a wrong and outdated view on strong type systems.

A good type system is also an ergonomic one. What people start to experience is that the compiler is actually a friend that helps you write code and keep yourself true to your own promises. When new people start Elm, PureScript or Haskell (or another lang with ADTs and Type Inference), they might be a bit overwhelmed with the paradigm shift, if coming elsewhere, but if you are new to programming, there's nothing inherently more difficult in Haskell than in other languages—the cost of wrong code is just apparent earlier.

It doesn't come down to trust, it comes down to the realization that your mind can keep track of less information than a computer, and that you, as a programmer, are forgetful and make mistakes. The compiler is there to help you when you stumble over your own feet.

NOTE: I'm only including strongly, statically typed languages with type inference in the above. "FP langs" by itself is far too broad to be a useful categorization.

Even experiences FP folks complain about how difficult it is to program in Haskell due to its purity. Further, the high barrier to entry you describe is an even bigger deal to organizations than to individuals. It’s a cost that needs to be paid for every employee. And it’s not just the language features, but FP languages tend to have issues like poor documentation, poor editor integrations, multiple standard libraries, multiple build tools, multiple string types, home-grown project file syntax, multiple preludes, many extensions, etc. All of these boost the learning curve in addition to the issues with the language itself.

In my limited experience with functional programming, I've come away with the impression that the problems you're describing are why you don't see a lot of companies that use FP exclusively.

But I think the advantages that OP is lauding are also there, and "space shuttle code" might just be where it shines. Reading that comment in this post made me immediately think of Haskell. The Clojure components at my company fits the "space shuttle" description of importance, and its dependability is striking compared to the rest of our code. Part of it may be that being written in a different language allows its concerns to be separate from the rest of the application too, but I do think the FP paradigm is simply good in this domain.

Sure, but I doubt all of Kubernetes is written in this style, so it’s probably not worth writing everything in Haskell. Note also that there’s nothing about FP that prohibits it from addressing the aforementioned practical problems. Some Haskell-like could swoop in and totally steal Go’s lunch if they would simply prioritize practicality over experimentation.

> Some Haskell-like could swoop in and totally steal Go’s lunch if they would simply prioritize practicality over experimentation.

I don't know. It seems like it would be easy enough to build an AST to make sure there were no unknown conditions that didn't lead to a return statement.

I don’t understand how your post relates to mine. I was saying that if a static functional language focused more on simplicity, readability, good tooling and documentation, etc then it would eat Go’s lunch without trading off any of Haskell’s important characteristics (I.e., robust type safety).

> I think that's a wrong and outdated view on strong type systems.

I wasn't really talking about type systems specifically, I was thinking along the lines of the Rust borrow checker here, and lower level programming like assembly and C.

> A good type system is also an ergonomic one. What people start to experience is that the compiler is actually a friend that helps you write code and keep yourself true to your own promises.

I see a lot of people make the mistake that type safe code is bug free code. "It compiles, therefore ship it."

> It doesn't come down to trust, it comes down to the realization that your mind can keep track of less information than a computer, and that you, as a programmer, are forgetful and make mistakes. The compiler is there to help you when you stumble over your own feet.

You trust the compiler to find bugs. Awesome. Luck be to you. I trust unit tests more than the compiler. Mostly because I wrote them. The compiler, I didn't.

You don't write the compiler, of course, but you do write or rather design the types that your program uses. The typechecker ensures that they're consistent within the system of logic that they set up.

By your logic, it's not enough to have faith in unit tests because you wrote them; you must also write the test framework and runner.

I have also developed a strong preference for the latter. I was always on the fence until I got my hands on generative testing (quickcheck, etc).

Now I want the powerful language and I can just slam it with generated tests to get the same level of confidence as the guardrail languages (in practice definitely, although I understand this is not true in theory, so unspit your coffee Haskell people).

Oh right and this is currently Clojure, so a functional language that definitely does help me make a great product. Less time implementing correctly means more time for product refinement.

Writing good generative tests is extremely laborious, in general. It's hard to get an informative sample of the input space.

As a professional Haskell dev, it definitely makes me more productive even discounting the higher quality of the results. Everything the language does for me is something less I have to think about it. And reusable abstractions, surprise, reduces work later making things go faster still.

Hopefully sometime soon I can share an example of this.

Your language example, and the burger example seems flipped. I assume you prefer artisan burgers, which means you like no language restrictions.

Badly chosen restrictions are not good, we can all agree. But what do good restrictions look like? Back in the day, programmers prided themselves on being able to do their own memory management, and bristled at the idea of a compiler or the runtime doing it for them. Now, that's the exception, as most of the time, we don't think about memory management in most languages we program in.

As time marches on, we'll find more of these restrictions that we all eventually agree are good practices, and the next generation of programmers will take it as a given in programming.

As a look beyond functional programming restrictions, I encourage you to check out Peter Alvaro's talk on Distributed Systems. Here, he talks about how queries over distributed systems is really hard to reason about, because time is now relative--there's no central clock to measure time. However, if we restrict ourselves to a language whose queries cannot express negation, a lot of the hard stuff about distributed systems go away.

https://www.youtube.com/watch?v=R2Aa4PivG0g