PEP 255: Simple Generators

[Greg Ewing]

David Eppstein wrote:
> 
> Ok, another mathematical one:
> 
>     def collatz(i):
>         yield i
>         if i % 2 == 0:
>             return collatz(i/2)
>         else:
>             return collatz(3*i+1)

Your proposal might work in the case where the recursion
involved is tail-recursion, but using tail-recursion in
place of iteration is a functional idiom that doesn't fit
very well in Python, IMO.

The cases where you would really want to use recursive
generators in Python are the non-tail-recursive ones,
and I don't think your proposal would help much there.

-- 
Greg Ewing, Computer Science Dept, University of Canterbury,	  
Christchurch, New Zealand
To get my email address, please visit my web page:	  
http://www.cosc.canterbury.ac.nz/~greg