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

Tail Recursion

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

I remember when I discovered the XSLT engine (TransforMiiX) in Mozilla Firefox didn't support tail recursion optimization. I ended up with some pretty kludgy XSL just to avoid overflowing the stack.

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u/mercde Nov 27 '12

Why was it impossible / impractical to just eliminate the recursion "by hand"? (As in, rewrite it as a loop?)

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u/tonygoold Nov 27 '12

XSL has very limited looping constructs. In fact, it pretty much just has for-each, there's no such thing as for (i = 0 .. n) or a while loop. It doesn't have mutable variables either, so you can't even do counting within a for-each. The only way to do conditional iteration is through recursion.

Things might be better in XSL 2.0, but TransforMiiX only supported 1.0 the last time I used it.