Using reduce() with tuples created by zip()

[bearophile]

Philippe Sigaud:

> We could also have a slightly different version that lazily 
> produces the
> intermediate results as a range. IIRC, it's called 'scan' in 
> Haskell.

It's already in Bugzilla:
http://d.puremagic.com/issues/show_bug.cgi?id=11084

Bye,
bearophile