I’ve been reading a lot of stuff about functional programming lately, and I can understand most of it, but the one thing I just can’t wrap my head around is stateless coding. It seems to me that simplifying programming by removing mutable state is like “simplifying” a car by removing the dashboard: the finished product … Read more
The ‘algebraic’ expression for algebraic data types looks very suggestive to someone with a background in mathematics. Let me try to explain what I mean. Having defined the basic types Product • Union + Singleton X Unit 1 and using the shorthand X² for X•X and 2X for X+X et cetera, we can then define … Read more
What does the term referential transparency mean? I’ve heard it described as “it means you can replace equals with equals” but this seems like an inadequate explanation. 14 Answers 14
Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago. Improve this question I have always thought that functional programming can be done in Python. Thus, I was surprised … Read more
Say I want to sum a.x for each element in arr. arr = [ { x: 1 }, { x: 2 }, { x: 4 } ]; arr.reduce(function(a, b){ return a.x + b.x; }); // => NaN I have cause to believe that a.x is undefined at some point. The following works fine arr = … Read more
In Java 8, I want to do something to an Optional object if it is present, and do another thing if it is not present. if (opt.isPresent()) { System.out.println(“found”); } else { System.out.println(“Not found”); } This is not a ‘functional style’, though. Optional has an ifPresent() method, but I am unable to chain an orElse() … Read more
I understand Ruby and Python’s yield. What does Scala’s yield do? 10 Answers 10
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 8 years ago. Improve this question I see a lot of talk on here about functional languages and stuff. Why would … Read more
I have heard the term “coalgebras” several times in functional programming and PLT circles, especially when the discussion is about objects, comonads, lenses, and such. Googling this term gives pages that give mathematical description of these structures which is pretty much incomprehensible to me. Can anyone please explain what coalgebras mean in the context of … Read more
filter, map, and reduce work perfectly in Python 2. Here is an example: >>> def f(x): return x % 2 != 0 and x % 3 != 0 >>> filter(f, range(2, 25)) [5, 7, 11, 13, 17, 19, 23] >>> def cube(x): return x*x*x >>> map(cube, range(1, 11)) [1, 8, 27, 64, 125, 216, 343, … Read more
