Why I Prefer Functional Programming • Hacker News Board

Re: Why I Prefer Functional Programming

#21

Post by pessimizer » Sat, Oct 31, 2020, 8:04 PM UTC

spekcular wrote: post #18

Syzygies wrote: post #8

Functional programming appeals to many of us for reasons other than these practical considerations: Functional programming feels like reasoning in algebra. As in Modern Algebra for math majors (groups, rings, fields) and beyond. There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order i…

> There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order in mathematics crosses a similar threshold, as it becomes sufficiently structured to support algebraic reasoning. The subjective experience is like ice melting into a churning liquid, or a land-locked creature learning to fly. O…

> There are plenty of languages where one can get parallelism with just a few extra lines of code; Julia comes to mind immediately.

Julia is a multi-paradigm language, but it is heavily Erlang inspired (another multi-paradigm language, but primarily functional.)

Re: Why I Prefer Functional Programming

#22

Post by adwn » Sat, Oct 31, 2020, 8:16 PM UTC

spekcular wrote: post #18

Syzygies wrote: post #8

Functional programming appeals to many of us for reasons other than these practical considerations: Functional programming feels like reasoning in algebra. As in Modern Algebra for math majors (groups, rings, fields) and beyond. There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order i…

> There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order in mathematics crosses a similar threshold, as it becomes sufficiently structured to support algebraic reasoning. The subjective experience is like ice melting into a churning liquid, or a land-locked creature learning to fly. O…

> In particular, a few years ago it seemed like the people implementing parallel Haskell features didn't understand or care about fundamental things like cache locality.

That's the main issue which FP-for-parallel-execution proponents don't seem to get: Identifying independent (and therefore parallelisable) computations isn't the hard part, but planning the data layout and partitioning so that all your parallelism isn't eaten up by synchronization and data movement between cores.

Re: Why I Prefer Functional Programming

#23

Post by adwn » Sat, Oct 31, 2020, 8:25 PM UTC

Syzygies wrote: post #8

Functional programming appeals to many of us for reasons other than these practical considerations: Functional programming feels like reasoning in algebra. As in Modern Algebra for math majors (groups, rings, fields) and beyond. There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order i…

> To this day it has the best implementation of parallelism; one can achieve a 7x speedup on 8 cores by adding a handful of lines to a program.

Eh, you can achieve the same in Rust using rayon, this isn't exclusive to Haskell or FP. Do you have an example in Haskell, where you get an effortless speedup which wouldn't be easy in another language?

Re: Why I Prefer Functional Programming

#24

Post by bachmeier » Sat, Oct 31, 2020, 8:35 PM UTC

Requiring a functional programming approach when you teach makes your life much easier. I teach a computationally-intensive course for advanced economics PhD students. These days I have them think carefully through their problem, set up a recursion, and make one call to reduce. The vast majority of problems fit into this framework. I no longer have to work my way through 500-line monsters that look like entries in an obfuscated Perl competition. I read a few lines of code, I know exactly what it does, and I get on with my life.

Re: Why I Prefer Functional Programming

#25

Post by jgilias » Sat, Oct 31, 2020, 8:37 PM UTC

adwn wrote: post #23

Syzygies wrote: post #8

Functional programming appeals to many of us for reasons other than these practical considerations: Functional programming feels like reasoning in algebra. As in Modern Algebra for math majors (groups, rings, fields) and beyond. There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order i…

> To this day it has the best implementation of parallelism; one can achieve a 7x speedup on 8 cores by adding a handful of lines to a program. Eh, you can achieve the same in Rust using rayon, this isn't exclusive to Haskell or FP. Do you have an example in Haskell, where you get an effortless speedup which wouldn't be easy in another language?

Yeah, but Rust isn't exactly a counter example, I think. It's heavily inspired by Haskell, its type system, as well as FP in general. So, it sort of inherits (pun not intended) its parallelization capabilities from that.

Re: Why I Prefer Functional Programming

#26

Post by curryhoward » Sat, Oct 31, 2020, 8:44 PM UTC

I like to think there is a nice pun here, that functional programming is "timeless" in two simultaneous ways:

(1) As mentioned in the article, values are immutable and side effects are reified so you do not have to reason about time. Instead, you can reason equationally, which unlocks some nice benefits related to refactoring, reasoning about correctness and concurrency, testing, reproducibility, etc.

(2) Functional programming is based on well-behaved mathematical foundations and so is more stable than the other programming paradigms. Object-oriented programming is a constantly moving target because it doesn't have a principled formal foundation (despite many attempts to establish one on an ex post facto basis), whereas functions are "timeless" in the sense that they're here to stay.

It's not without tradeoffs of course, but if you're willing to have an open mind about how computers should be programmed and forego some things that are so pervasive in traditional programming (e.g., unrestricted side effects), the payoff is huge.

Re: Why I Prefer Functional Programming

#27

Post by darksaints » Sat, Oct 31, 2020, 8:52 PM UTC

jgilias wrote: post #25

adwn wrote: post #23

Earlier quoted context omitted.

> To this day it has the best implementation of parallelism; one can achieve a 7x speedup on 8 cores by adding a handful of lines to a program. Eh, you can achieve the same in Rust using rayon, this isn't exclusive to Haskell or FP. Do you have an example in Haskell, where you get an effortless speedup which wouldn't be easy in another language?

Yeah, but Rust isn't exactly a counter example, I think. It's heavily inspired by Haskell, its type system, as well as FP in general. So, it sort of inherits (pun not intended) its parallelization capabilities from that.

Heavily? It's actually heavily inspired by ML (SML/OCaml), not Haskell. Most of its functional programming attributes originated in SML, and has avoided most of the things that make Haskell unique. Really it is just type classes that came from Haskell.

Re: Why I Prefer Functional Programming

#28

Post by jeffreygoesto » Sat, Oct 31, 2020, 9:06 PM UTC

adwn wrote: post #23

Syzygies wrote: post #8

Functional programming appeals to many of us for reasons other than these practical considerations: Functional programming feels like reasoning in algebra. As in Modern Algebra for math majors (groups, rings, fields) and beyond. There's a saying in mathematics that when any field matures it turns into algebra. Life crossed a threshold from chemistry to biology on Earth, and developed exponentially from there. Order i…

> To this day it has the best implementation of parallelism; one can achieve a 7x speedup on 8 cores by adding a handful of lines to a program. Eh, you can achieve the same in Rust using rayon, this isn't exclusive to Haskell or FP. Do you have an example in Haskell, where you get an effortless speedup which wouldn't be easy in another language?

Isn't the speedup a direct result of immutable data more than a specific language?

Re: Why I Prefer Functional Programming

#29

Post by nendroid » Sat, Oct 31, 2020, 9:11 PM UTC

I disagree with the higher order functions thing. Writing functions that receive other functions as input can lead to over complicated code that's really hard to read. It's literally the same thing as dependency injection just with functions instead of objects.

Use sparingly. I would avoid altogether except for common ones like map, reduce and filter.

Functional programming promotes the idea of composition of morphisms and point free programming. I would use this in place of Object composition/dependency injection/higher order functions or whatever you want to call it.

Re: Why I Prefer Functional Programming

#30

Post by sidpatil » Sat, Oct 31, 2020, 9:20 PM UTC

curryhoward wrote: post #26

I like to think there is a nice pun here, that functional programming is "timeless" in two simultaneous ways: (1) As mentioned in the article, values are immutable and side effects are reified so you do not have to reason about time. Instead, you can reason equationally, which unlocks some nice benefits related to refactoring, reasoning about correctness and concurrency, testing, reproducibility, etc. (2) Functional…

This is known as combinatorial logic, contrasted with sequential logic which is "timeful".