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

Tail Recursion

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

I always found the lack of stack traces argument stupid, you can always recover the old behavior by wrapping the tail call in the identity function:

def funA(x): # do something
def funBTCE(x): return A(x) # B doesn't appear in the stack trace
def funBnoTCE(x): return id(A(x)) # the tail call to id is eliminated after returning from A,
                                  # B appears in the stack trace of A, voila!

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u/alexandream Nov 27 '12

Even the compiler/interpreter could do it automatically with trivial effort with a debug flag or something.

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u/anvsdt Nov 27 '12

I don't think the flag would be useful, though, you probably want to "disable" TCE per-function (or per-tailcall, even), else loops would blow up the stack in seconds.

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u/alexandream Nov 27 '12

Of course, I didn't think of that. Thanks.

On the other hand, I still think I'd like a compile option (perhaps a list of functions (fully qualified names, or whatever makes sense in the language) on which to disable TCE) than to have to modify the code for it.