Re: named-let

[Stefan Monnier]

>> [ TCO has also undesirable interactions with debugging/tracing, but
>>   I think that would be a secondary concern which should be
>>   manageable somehow.  ]
>
> It's also a change in semantic as one must assume that `bar' is not
> redefining `foo'.
>
> (defun foo ()
>   (bar)
>   (foo))

I think there's a bit of confusion: you can have TCO without having to
pay any attention to whether `bar` changes `foo`.  True TCO will also
avoid eating up stack space when you have code like

    (defun foo (x)
      (baz (1+ x)))

or

    (defun foo (x)
      (funcall (if (something) #'bar #'foo) (1+ x)))

or

    (defun foo (x)
      (let ((k (lambda (y) (foo (1+ x)))))
        (k 5)))

or ... and that doesn't depend on analyzing the code at all.

IOW, it shouldn't matter whether it's a recursive call or whether it's
a call to "self": all calls in tail position would conceptually pop
their stack frame before jumping to the destination function.


        Stefan