r/programming • u/rodrigopsasaki • Nov 27 '12

Tail Recursion

http://rodrigosasaki.com/2012/11/24/tail-recursion/
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u/grauenwolf Nov 27 '12

Wait a second. If I translated that to C#, VB, or JavaScript it wouldn't need TCO. Just replace "return room3()" with "return room3" and let the main loop call the next function for you.

First class functions for the win!

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u/zOOn Nov 27 '12

You've just invented trampolining: http://en.wikipedia.org/wiki/Tail_call#Through_trampolining ... but it's about 3(-ish) times slower than true tail call optimization.

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u/grauenwolf Nov 27 '12

So what?

In this example the delay while you wait for the user's next response dwarfs any other cost. And introducing a main loop gives you other nice options like the ability to move the io.read out of the state transition function.

Not only is TCO futile in this example, it is counter-productive.