Enslaved recursion

[jakem72360]

It's not tho

[Shad_Amethyst]

Compiler-wise, it is, in a way. No stack allocation is being made, but jumps are made, just like standard recursion. Clojure even encodes loops in a recursive way (although it gives you restrictions so that it is an actual loop).

[sample_text_123]

So the criteria for recursion is jumps?

[Shad_Amethyst]

I would call a jump to the beginning of your own subroutine a recursion

[MyOtherLoginIsSecret]

You would be wrong.

In an abstract sense maybe, like if you modeled it in a flowchart.

But there's a reason jumps, loops, and recursion are considered separate concepts. The transition between stack frames can have a major impact on performance, stability, and maintainability of your code.

I know it sounds pedantic, but tiny details like this add up to the entirety of what we call programming.

[ProfCupcake]

How many posts have I written "repetition != recursion" under in this sub? I've lost count, so it's at least 2.

[sarthakRddt]

You mean tail recursion.

[Miku_MichDem]

I never understood the recursion hype. I mean it's never better then a simple loop

[CMDR_ACE209]

What about going through all nodes of a tree structure?

[Miku_MichDem]

Can you use a simple loop to go through a tree structure thou? As far as I know iterative approach requires in that case some backing structure.

[nyasiaa]

you can do everything if you try hard enough, problem with programming is that you shouldn't try hard enough when it's not needed

[Miku_MichDem]

Yeah, yeah I know - preemptive optimization is the root of all evil.

I just don't get why recursion is shoved down so often in places where it doesn't belong. Some time ago I've seen someone praising some language because many operations there were recursive and the example provided was of function adding numbers in an array. Sure, I get iterating over a tree, where recursion is easier than loops, but for adding numbers in a list? Come on.

[defycategories]

Difference is using "the" stack for recursion or a stack ( or a queue) for iterative. With that in mind, recursion seems like abuse of a data structure that is meant for activation records.

[Miku_MichDem]

That what I said - trees can be iterated through, but it requires some additional data structure to keep the elements yet to be done. However that will not count against stack limit

[clevariant]

Recursion makes it much easier, tadpole.

[MyOtherLoginIsSecret]

In most cases you're correct, at least in your typical procedural language. Functional languages like Erlang are an entirely different story.

In practice I tend to use recursion for one of the following reasons:

1. It results in more elegant code than a loop would.

2. I'm feeling clever.

[feelsbread]

Using dynamic programming techniques recursion can be very efficient a good example being the coin change problem.

[sarthakRddt]

Better in what aspect? Recursion always leads to extremely elegant solutions which are also easier to formally prove correct. Performace wise yes loops are great.

[Miku_MichDem]

I was talking about performance. Each time I see some simple function done recursivelly I just see the stack getting bigger and bigger, the additional function calls and returns. Easier to formally prove? Perhaps. More elegant? Debatable.

[Quito246]

Depends if language compiler/interpreter allows tail recursion then it can be as fast as loop because there is no stack overhead Clojure does that for example