On Jun 5, 6:49 am, a...@pythoncraft.com (Aahz) wrote: > In article > <05937a34-5490-4b31-9f07-a319b44dd...@r33g2000yqn.googlegroups.com>, > Michele Simionato <michele.simion...@gmail.com> wrote: > > > > >Actually, in Scheme one would have to fight to define > >a list comprehension (more in general loops) working as > >in Python: the natural definition works as the OP wants. See > >http://www.artima.com/weblogs/viewpost.jsp?thread=3D251156and the > >comments below for the details. > > This URL isn't working for me, gives 500.
Anyway, the point is that to explain Python behavior with closures in list/generator comprehension it is not enough to invoke late bindings (Scheme has late bindings too but list comprehension works differently). The crux is in the behavior of the for loop: in Python there is a single scope and the loop variable is *mutated* at each iteration, whereas in Scheme (or Haskell or any other functional language) a new scope is generated at each iteration and there is actually a new loop variable at each iteration: no mutation is involved. Common Lisp works like Python. It is a design decision which at the end comes down to personal preference and different languages make different choices with no clear cut winner (I personally prefer the more functional way). -- http://mail.python.org/mailman/listinfo/python-list
