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Comment by Gibbon1 | Hacker News Reader

Winging off a comment above, I find recursion generally intuitive, occasionally useful, and really really boring.

Offhand years ago I used a dialect of C that had no recursion so I can see both sides of this argument. On the one hand, there is a pain point when you don't have access to recursion. On the other, boy can a compiler that eschews recursion produce small and fast code. (Because without recursion the call graph is acyclic)

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I wouldn't call recursion boring. Quicksort in Haskell is probably my favorite two lines of code:

  quicksort [] = []
  quicksort (x:rest) = quicksort [y | y <- rest, y <= x] ++ [x] ++ quicksort [y | y <- rest, y > x]

It's been discussed before, but that's not really quicksort though (since it's not in-place)[0]

0: http://stackoverflow.com/q/7717691/1235548

Do we know that for sure? I mean - could a sufficiently smart compiler actually create machine code which _did_ do it in-place?

This variant (with the <= comparison) takes c N^2 on lists of length N that a repeated constant ( http://www.win-vector.com/blog/2008/04/sorting-in-anger/ ).

> On the other, boy can a compiler that eschews recursion produce small and fast code.

Are you really implying that if recursion was turned off in a modern compiler it could create better code?

That would be hard to turn off. My experience is with a old 8051 compiler. Notable feature was it never pushed anything on the stack other than return addresses. Used the call tree to fold parameters and local variables into a small amount of common memory. I think modern compilers deal with this situation by in-lining. But that can cause the code size to swell vs calling a subroutine that accesses globals.

Just saying, you add a feature to a language, you will pay something for it.

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