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I learned Haskell in just 15 years

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Re: I learned Haskell in just 15 years

#51

Post by Dylan16807 »

elbear wrote: post #46
Dylan16807 wrote: post #44

Earlier quoted context omitted.

I was looking at both rules, and specifically I was using the long version where you said "it doesn't assign them to some other global variable that you have to track down". If you pass in a mutable object then that's not "some other global variable". If I interpret "It only outputs its results" in a very strict way, that still allows having output and in/out parameters. The latter of which can break purity. Though y…

So, another definition of a pure function is that, for a particular input it will always return the same output. Your example respects the rule: f({x=1}) == 1 f({x=2}) == 2 But it's true that the two rules I gave are not enough to make a function pure. Because I didn't say anything about I/O. So, a function that follows the rules about inputs and outputs, could still do I/O and change its outputs based on that. Start…

> Your example respects the rule:

Every definition of purity I can find that talks about objects/references says that if you pass in the same object/reference with different contents then that's not pure.

Your version differs from mine on that aspect. It passes two unrelated objects.

> Starting from the question that gave birth to this whole thread: "What's the benefit of learning a PURE functional programming language..."

I interpret saying a language is "purely functional" as being more about whether you're allowed to write anything that isn't functional. I can talk about BASIC being a "purely iterative" language or about "pure assembly" programs, without any implication of chunks of code being pure.

Re: I learned Haskell in just 15 years

#52

Post by chipdart »

mrkeen wrote: post #15
nequo wrote: post #6

Earlier quoted context omitted.

That’s interesting because F#’s OOP, as someone who knows neither C# nor Java, makes it more intimidating to me than OCaml. Also interesting that when FP is mentioned, Hindley-Milner is implicitly understood to be part of FP too even though it doesn’t have to be. Clojure emphasizes immutability and FP but with dynamic typing and everything that comes with that.

> Clojure emphasizes immutability Is "emphasizes" just another word for second-class support? C++ emphasizes the importance of memory safety.

> Is "emphasizes" just another word for second-class support?

I don't know what's your personal definition of "second-class support" but what it means is that it's explicitly supported by the language.

Re: I learned Haskell in just 15 years

#53

Post by dejvid123 »

munchler wrote: post #2

Cute. All kidding aside, though, functional programming is worth the effort to learn, and it doesn't actually take 15 years. The payoff is at the end of the article: "It’s quite natural to program in Haskell by building a declarative model of your domain data, writing pure functions over that data, and interacting with the real world at the program’s boundaries. That’s my favorite way to work, Haskell or not." Haskel…

I would suggest Scala as FP for beginners. It doesnt forces you to do pure functions. And its really beginners friendly to start with.

Re: I learned Haskell in just 15 years

#54

Post by agumonkey »

TrackerFF wrote: post #12

What's the benefit of learning a PURE functional programming language, opposed to just using a language which has adapted the best bits and pieces from the functional programming paradigm? Given that you want write code that sees "real world" use, and is used to handle data and events from the real world. To me, sometimes the line between optimized code and intellectual curiosity blurs.

In a way, one benefit is the whole ecosystem / culture / idioms built on top. Haskellers went further in that direction than most languages (except maybe scalaz and some hardcore typescript devs).

Re: I learned Haskell in just 15 years

#55

Post by simiones »

tome wrote: post #41
fire_lake wrote: post #35

Earlier quoted context omitted.

Is Haskell pure? It has exceptions You can divide by zero It has unsafe IO primitives

You're right: "pure" is not a well-defined concept. The well-defined concept that describes Haskell's benefits in this regard is "referential transparency". That means that this code let x = in ... x ... x ... (i.e. defining a variable x and then using it some number of times) is equivalent to ... ... ... Seen in the opposite direction (transforming the bottom code to the top code) this means that extracting repeated…

Well, technically that isn't true if you use, for example, unsafePerfomIO in the defintion of x. Referential transparency is still a spectrum, just like purity. Haskell is much closer to purity than the vast majority of languages out there.

Also, even if Haskell were perfectly pure, the fact that it uses lazy evaluation is far more important to actually being able to make use of referential transparency. In a strict language you will still see a massive performance differences if replacing the first version with the second, in the most common cases.

Re: I learned Haskell in just 15 years

#56

Post by mrkeen »

Dylan16807 wrote: post #33
elbear wrote: post #26

Earlier quoted context omitted.

What's the benefit? You start to see functions as self-contained things, as lego blocks. All the logic of the function is there in the function. It only works on values it receives as inputs (it can't read global variables). It only outputs its results (it doesn't assign them to some other global variable that you have to track down). This makes your code modular. You can add a function in a chain of functions, if yo…

Is there a benefit if you're already familiar with writing functions like that? Is it wrong for me to expect that most programmers are already familiar with functions that only use their inputs, but treat that style as significantly more optional? I wrote pure functions for a minute there but that's not the same, a function that only uses its inputs can modify an object while a pure function would have to return a ne…

> Is it wrong for me to expect that most programmers are already familiar with functions that only use their inputs

They'll experience no friction when using Haskell then. Haskell only refuses to compile when you declare "Oh yeah I know functions from other languages this is easy" but then do some mutation in your implementation.

Re: I learned Haskell in just 15 years

#57

Post by MrBuddyCasino »

cornel_io wrote: post #39
anon291 wrote: post #13

Earlier quoted context omitted.

Realistically we don't but it's very rare to meet a programmer who understands these distinctions thats not also a great functional programmer. This is my experience after spending five years as a Haskell programmer and managing a Haskell team for several years and now moving back to the c++ world to play with AI. I know lots of good c++ programmers working on cutting edge stuff, real experts in their field, but they…

I've actually had to fire a technically exceptional Haskell programmer because of the damage they did to our C# codebase (and arguably moreso, the team). Sometimes it's not a matter of talent or skill, but culture fit. In my experience FP-aligned people on non-FP projects tend to be more likely to overengineer, more prone to argue in favor of the Great Rewrite For No Reason Except Aesthetics, and more likely to abuse…

This is my experience, too. Some of the worst code I‘ve seen was a Haskell guy who first built his own (reactive?) concurrency framework and then implemented the actual functionality in completely unidiomatic and undocumented Java.

Some people don’t understand that the „best solution“ is not necessarily equal to the most beautiful abstraction they can think of.

Re: I learned Haskell in just 15 years

#58

Post by keybored »

TrackerFF wrote: post #12

What's the benefit of learning a PURE functional programming language, opposed to just using a language which has adapted the best bits and pieces from the functional programming paradigm? Given that you want write code that sees "real world" use, and is used to handle data and events from the real world. To me, sometimes the line between optimized code and intellectual curiosity blurs.

> Given that you want write code that sees "real world" use, and is used to handle data and events from the real world.

Real world? As opposed to what?

Is there any benefit to answering such polemical questions as if they are not rhetorical?

Re: I learned Haskell in just 15 years

#59

Post by Joker_vD »

richrichie wrote: post #9
munchler wrote: post #2

Cute. All kidding aside, though, functional programming is worth the effort to learn, and it doesn't actually take 15 years. The payoff is at the end of the article: "It’s quite natural to program in Haskell by building a declarative model of your domain data, writing pure functions over that data, and interacting with the real world at the program’s boundaries. That’s my favorite way to work, Haskell or not." Haskel…

But why do we need Haskell for this?

Because for some reason there are no pure strict-by-default languages around.

Re: I learned Haskell in just 15 years

#60

Post by foldr »

Joker_vD wrote: post #59
richrichie wrote: post #9

Earlier quoted context omitted.

But why do we need Haskell for this?

Because for some reason there are no pure strict-by-default languages around.

Elm is one example of such. However, it's also an illustration of why these languages are rare. With a strict semantics there's an almost unbearable temptation to add library functions with side effects. Elm only avoided this fate by giving its BDFL strict control over which packages could access the JS FFI. But that upset a lot of people.
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