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Ask HN: The best plan to learn the functional programming paradigm

2 points by digamber_kamat ↗ HN
I have enough experience in programming in JAVA,PHP and JavaScript. I am curious to learn functional programming paradigm. I dont think my knowledge of FP is going to have any impact on my career in near future. I want to learn it only for the knowledge sake and who knows it might help me do my existing stuff in a better way.

I need help in preparing a plan which is something like below.

1. Which should be my first FP language ? 2. Should I start learning the languages directly or gather some mathematical background from any other source ? 3. Which should be the first book/videos I should go through ? 4. Can anyone suggest me a sample project that might help me build and apply all the concepts? When I was learning JAVA we had built a pet store and when I learned PHP I had built a social networking app.

7 comments

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[dead] umeshkacha
Start learning Scala. Its JVM language you will have Java feeling as you can use Java libraries in Scala. Its very good FP language to learn. Its next Java I believe.
thaumaturgy
If you're familiar with JavaScript, then some of its advanced features can "ease" you into functional programming:

1. Closures. Closures are handy for lots of things, but a lot of people (myself included) have said that they had difficulty understanding them at first. I don't know what your knowledge level is so I won't presume that you need a tutorial, but if you do, a lot of people here should be able to help.

2. Anonymous functions. You can create functions on-the-fly, you don't have to name them, then store them in a variable and call the variable.

I don't really "know" any functional programming languages, but these things are apparently common concepts in that arena, and playing around with them in a language that you're familiar with might make it easier for you.

I'd be willing to go into more detail if you'd like, or provide examples. I have tens of thousands of lines of JavaScript, and a lot of it takes advantage of JS' functional programming stuff.

digamber_kamat
I love both Closures as well ans Anonymous functions.
wagemanh4x
If you have already learned two languages by building things and it is a model that has worked for you then use the same model. When it stops working improve the model or throw it out and work on a different learning method.

I learned Lisp by building.

I recommend you build and fail and build more. You will learn a lot that way.

edit: grammar fail

jamesbritt
You first concern will be to define just what makes for a functional programming language. Is having first-class functions enough? What about referential transparency or immutable state? Does it have to adhere to the Lambda Calculus?

You might get some ideas here: http://en.wikipedia.org/wiki/Functional_programming

However, "What's FP?" is ripe for flame wars so you may do better to ask abut languages that offer specific characteristics rather than whether or not people call it a functional programming language.

That said, I'd suggest Haskell. I mean, what the hell, might as well go hardcore. Start with Learn You a Haskell For Great Good, and/or Real World Haskell.

Both available free online, both available as for-purchase books, both well worth the money.

http://learnyouahaskell.com/chapters

http://book.realworldhaskell.org/read/

digamber_kamat
Thanks this is exactly the kind of advice I was looking for.
tjr
Which language to learn is a matter of taste. I personally think Scheme would be a good choice.

Learning the mathematical background first might be a good idea if you're a mathematician. Otherwise, getting at least some practical exposure in a language may cause the math to make more sense to you, should you decide to study it later.

For Scheme, some good books include: The Little Schemer and Structure and Interpretation of Computer Programs.

A good sample project might be to build some sort of language intepreter. For Scheme-based ideas, take a look at the book Essentials of Programming Languages. One of the early projects in that book is to build an arithmetic expression evaluator; by that point, you should be well on your way to thinking functionally.