[Python-Dev] list comprehensions again...

Paul Prescod paul@prescod.net
Tue, 11 Jul 2000 19:44:10 -0500

Thomas Wouters wrote:
> ...
> Well, not really. It doesn't create a new list, only a tuple to hold lists
> to iter over (in order to pass it to the opcode as a single PyObject) and
> similar for the resulting objects. It's definately more efficient than the
> map() solution (and different, see below ;)

Nevertheless, I think it is worth asking whether a parallel() or merge()
function can do the same thing. It's not like the semicolon syntax
screams out the right answer. The parallel function could return an
iteratable object that generates tuples on demand. A function can be
used in contexts other than a for loop.

If we make functions like parallel and range not only builtin but
non-overridable, we can do all sorts of optimizations in the bytecode
compiler (and other compilers). In other words we can "inline" them when
they are used in simple contexts.

 Paul Prescod - Not encumbered by corporate consensus
Simplicity does not precede complexity, but follows it. 
	- http://www.cs.yale.edu/~perlis-alan/quotes.html