On Tue, 23 Sep 2008 06:41:33 -0700 (PDT), sturlamolden <[EMAIL PROTECTED]>
wrote:
On Sep 23, 3:13 am, process <[EMAIL PROTECTED]> wrote:
Why doesn't Python optimize tailcalls? Are there plans for it?
Because Python is a dynamic language. While a function is executing,
its name may be bound to another object. It may happen as a side
effect of what the function is doing, or even from another thread. The
compiler has no way of knowing that.
That's not the reason. It's not particularly hard to implement TCE for
Python. Instead, Guido has repeatedly given the reason as his feeling
that recursion is not the most natural way to express most algorithms
in Python. Adding TCE to the runtime would encourage people to write
(or continue to write) highly recursive algorithms, which would go
against what Guido thinks is "Pythonic". Here's a quote from him on
the topic:
But I have a problem with tail recursion. It's generally requested by
new converts from the Scheme/Lisp or functional programming world, and
it usually means they haven't figured out yet how to write code
without using recursion for everything yet. IOW I'm doubtful on how
much of a difference it would make for real Python programs (which,
simplifying a bit, tend to use loops instead of recursion).
Jean-Paul
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