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Functional Programming For The Rest of Us

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Re: Functional Programming For The Rest of Us

#11

Post by anthony_d »

eof wrote: post #4

Aside: I am maybe 50-60 hours into my first haskell project using yesod. I have read about half of "real world haskell" and about half of "learn you a haskell". Other than this, all of my experience is in iterative languages. (c++,python,php). One thing that comes up is "if your program compiles it's almost certain to be correct"; and it has been true again and again for me. It's an odd, eery feeling that honestly I…

I'm in pretty much the same boat. I feel kinda dirty playing with the type signatures to see what compiles, but if it compiles in Haskell it probably works.

Re: Functional Programming For The Rest of Us

#12

Post by tmhedberg »

chousuke wrote: post #7
eof wrote: post #4

Aside: I am maybe 50-60 hours into my first haskell project using yesod. I have read about half of "real world haskell" and about half of "learn you a haskell". Other than this, all of my experience is in iterative languages. (c++,python,php). One thing that comes up is "if your program compiles it's almost certain to be correct"; and it has been true again and again for me. It's an odd, eery feeling that honestly I…

I think the "if it compiles, it works" has to do with Haskell's type system being much more expressive than most static languages, and that most of your code will be declarative and pure. Purity helps because your program will necessarily be composed of small, self-contained modules (usually functions) that have no implicit dependencies. The type system helps because you can encode a lot of the code's intent in type…

Agreed; after getting used to working with Haskell's type system, I've found it kind of painful to use languages with weaker, less expressive type systems (which unfortunately, is basically every practical language other than Haskell). The ability to transform all manner of bugs into compile-time errors via the typechecker is indispensable. Once you start digging into GHC extensions like GADTs and type families, it gets even better. I never feel nearly as confident about the correctness of code I write in, say, Python, even when using a full test suite.

Re: Functional Programming For The Rest of Us

#14

Post by spacemanaki »

dustingetz wrote: post #10

i wrote this article off about when it makes incorrect comparisons between immutable values and final variables. someone who read it, is the rest of the article worth reading, or even accurate? there's certainly a need for articles like this, targetting an audience of java devs, if only they were correct. I haven't found much.

Yes, it's worth reading and it's basically accurate, although I'm not sure the accuracy is really as important as the general big picture, since there aren't that many examples.

Is there something specific that you can point out where the article is actually incorrect? There are only a few paragraphs in the beginning that mention final variables (and those only use Java primitives). I agree that there's a distinction to be made but I don't know how useful that would be in this kind of article.

If you're going to be splitting hairs over immutable values and final variables, you're probably not the target audience. On the other hand, Java devs who can't be bothered to finish a 20 page article probably aren't either.

FWIW, I think that Rich Hickey's Clojure videos and some of his more general talks on state, time and identity are probably some of the best "intros to FP for Java devs" out there.

Re: Functional Programming For The Rest of Us

#15

Post by gtani »

fahad-sheikh wrote: post #13

I found this article very useful, and helpful in de-mystifying the world of functional programming. Are there other articles that cover functional programming theory in plain words like this?

Glad you asked! I did this in about 7 minutes, but I could spend a week talking about how lispers, ML, clojure scala and haskell approach this. http://www.reddit.com/r/haskell/comments/qxmh3/what_are_some...

http://stackoverflow.com/questions/tagged/functional-program...

esp this one (Harrop, Ramsey, Brian are FP heavyweights

http://stackoverflow.com/questions/485418/distinctive-traits...

Re: Functional Programming For The Rest of Us

#16

Post by tomp »

rauljara wrote: post #9

Kudos to the piece for being well written, readable, and clear. But I'm worried about a "for the rest of us" that starts off with first Plato and then lambda calculus. The problem with "the rest of us" is that these concepts aren't inherently neat. Disclaimer: I'm not one of "rest of us". I'm learning Haskell, just because I enjoy having to think in a new way. A lot of FP explanations start off with immutability. Aft…

This article is another one of those that confuses functional programming with pure programming (which is, I believe, by definition also functional).

You can do a lot of functional programming in a language where values are mutable. I use it all the time in python: the map and filter functions, list comprehensions, zip, ... For me, functional programming means having first-class functions that can be passed to/from other functions. A standard library of common functional combinators help, but you can always write your own.

Funny, but some of the most often mentioned functional languages, such as OCaml and Scala, allow liberal use of mutable variables. They just make it a bit harder/more explicit, so the programmer has to give more consideration into it.

Re: Functional Programming For The Rest of Us

#17

Post by jshen »

tomp wrote: post #16
rauljara wrote: post #9

Kudos to the piece for being well written, readable, and clear. But I'm worried about a "for the rest of us" that starts off with first Plato and then lambda calculus. The problem with "the rest of us" is that these concepts aren't inherently neat. Disclaimer: I'm not one of "rest of us". I'm learning Haskell, just because I enjoy having to think in a new way. A lot of FP explanations start off with immutability. Aft…

This article is another one of those that confuses functional programming with pure programming (which is, I believe, by definition also functional). You can do a lot of functional programming in a language where values are mutable. I use it all the time in python: the map and filter functions, list comprehensions, zip, ... For me, functional programming means having first-class functions that can be passed to/from o…

You must have read a different article than the one I read.

"Functional programming is a practical implementation of Alonzo Church's ideas. Not all lambda calculus ideas transform to practice because lambda calculus was not designed to work under physical limitations. Therefore, like object oriented programming, functional programming is a set of ideas, not a set of strict guidelines. There are many functional programming languages, and most of them do many things very differently. In this article I will explain the most widely used ideas from functional languages"

No where does he say that functional programming is pure programming.

Re: Functional Programming For The Rest of Us

#18

Post by gtani »

chousuke wrote: post #7
eof wrote: post #4

Aside: I am maybe 50-60 hours into my first haskell project using yesod. I have read about half of "real world haskell" and about half of "learn you a haskell". Other than this, all of my experience is in iterative languages. (c++,python,php). One thing that comes up is "if your program compiles it's almost certain to be correct"; and it has been true again and again for me. It's an odd, eery feeling that honestly I…

I think the "if it compiles, it works" has to do with Haskell's type system being much more expressive than most static languages, and that most of your code will be declarative and pure. Purity helps because your program will necessarily be composed of small, self-contained modules (usually functions) that have no implicit dependencies. The type system helps because you can encode a lot of the code's intent in type…

not the most powerful system imaginable for that purpose

had to ask, what is more powerful, agda/coq/other?

Re: Functional Programming For The Rest of Us

#20

Post by evincarofautumn »

rauljara wrote: post #9

Kudos to the piece for being well written, readable, and clear. But I'm worried about a "for the rest of us" that starts off with first Plato and then lambda calculus. The problem with "the rest of us" is that these concepts aren't inherently neat. Disclaimer: I'm not one of "rest of us". I'm learning Haskell, just because I enjoy having to think in a new way. A lot of FP explanations start off with immutability. Aft…

I agree. It’s fun for someone like me who likes learning new stuff for its own sake, but I think the “Rest of Us” might feel a bit left out without more practical examples. But hey, that’s the same mistake I made when I last wrote about concatenative programming. Hindsight’s 20/20.
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