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FP-Go: Functional programming library for Golang

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Re: FP-Go: Functional programming library for Golang

#33

Post by [deleted] »

erik_seaberg wrote: post #25
duskwuff wrote: post #23

Earlier quoted context omitted.

> You can't A(B()) if B returns two values. You can if A is a function which takes two arguments, e.g. package main import "log" func A(x, y int) { log.Printf("%d, %d", x, y) } func B() (int, int) { return 1, 2 } func main() { A(B()) } https://go.dev/play/p/Jp4B0L6NJj2

What you can't do is a(b(), c()) unless b and c return single values. And there are no slices or channels of tuples, return values must be destructured right away.

[deleted]

Re: FP-Go: Functional programming library for Golang

#34

Post by moonshxne »

Love expression-oriented pseudo-FP (F#, Scala, Rust), but I think this recent trend of trying to shoehorn Haskell-lite features into mainstream imperative languages is, to put it gently, extremely awkward.

That said, I actually do remember my first exposure to Golang being a blog post about using monads to avoid incessantly typing `if err != nil`. Very much like that original author, my personal values in software engineering just don't align with Go at all, and that should be OK!

Re: FP-Go: Functional programming library for Golang

#36

Post by physicles »

This is a tour de force, and it accomplishes the goal of enabling FP using the Go syntax and toolchain.

But code written using this library is no longer Go: most Go programmers can't grok it, and it's awkward to call normal Go libraries because there's no way to know if that function you're calling is pure.

If your goal is to "make it easy and fun to write maintainable and testable code in golang" by making pure functions first-class, is there another way to do that without inventing a new language?

From experience and inspired by Carmack's classic essay on FP in C++[1], I tend toward a functional style: minimize state, treat locals as const, avoid non-const globals, enable parallelism by isolating state. Go makes it easy to write static analysis tools, so go vet could be augmented to, for example, keep track of which functions are pure, and show some yellow underlines at those places where input parameters are mutated.

I'd use something like that.

[1] http://sevangelatos.com/john-carmack-on/

Re: FP-Go: Functional programming library for Golang

#37

Post by sambeau »

I’m sorry, but this is just awful.

  func TraverseTuple10[F1 ~func(A1) IOEither[E, T1], F2 ~func(A2) IOEither[E, T2], F3 ~func(A3) IOEither[E, T3], F4 ~func(A4) IOEither[E, T4], F5 ~func(A5) IOEither[E, T5], F6 ~func(A6) IOEither[E, T6], F7 ~func(A7) IOEither[E, T7], F8 ~func(A8) IOEither[E, T8], F9 ~func(A9) IOEither[E, T9], F10 ~func(A10) IOEither[E, T10], E, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) func(T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) IOEither[E, T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]]

Re: FP-Go: Functional programming library for Golang

#39

Post by [deleted] »

sambeau wrote: post #37

I’m sorry, but this is just awful. func TraverseTuple10[F1 ~func(A1) IOEither[E, T1], F2 ~func(A2) IOEither[E, T2], F3 ~func(A3) IOEither[E, T3], F4 ~func(A4) IOEither[E, T4], F5 ~func(A5) IOEither[E, T5], F6 ~func(A6) IOEither[E, T6], F7 ~func(A7) IOEither[E, T7], F8 ~func(A8) IOEither[E, T8], F9 ~func(A9) IOEither[E, T9], F10 ~func(A10) IOEither[E, T10], E, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, T1, T2, T3, T4, T…

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