On Jun 6, 12:06 am, Terry Reedy <tjre...@udel.edu> wrote: > Brian Quinlan wrote: > > > Sorry, I wasn't as precise as I should have been. > > > If you consider this example: > > (<expr> for x in y) > > > I thought that every time that <expr> was evaluated, it would be done in > > a new closure with x bound to the value of x at the time that the > > closure was created. > > > Instead, a new closure is created for the entire generator expression > > and x is updated inside that closure. > > Thanks you for explaining your confusion. Knowing what sort of > other-language-baggage people are being mislead by can only help in > explaining Python. But here is my question. In Python, > > g = (<expr> for x in iterable) > > is essentially an abbreviation for, and means the same as > > def _(it): > for x in it: > yield <expr> > g = _(iterable) > del _ > > Are there language in which a similar construct has an essentially > different meaning? > > Terry Jan Reedy
Yes, most functional languages have the concept of streams. You can even define a stream-comprehension that looks like Python generator comprehension but it is an essentially different thing. See for instance http://www.artima.com/weblogs/viewpost.jsp?thread=251159 -- http://mail.python.org/mailman/listinfo/python-list
