map/filter/reduce/lambda opinions and background unscientificmini-survey

[Christopher Subich]

Carl Banks wrote:
> I suspect you're misunderstanding what I mean by heavily functional.
<snip>
> Heavily functional programming is a different mindset altogether.  In
> heavily functional programming, things like maps and filters and
> function applications are actually what you're thinking about.  map
> isn't an indirect way to do a for loop; it's a direct way to do a map.

That's true; I'm more comfortable with procedural programming in 
general, but I had a few classes that used LISP and understand what 
you're talking about.

That said, Python itself is mostly a procedural language, with the 
functional tools really being bolted on[1].  When we're talking about 
Py3K, I think we're really talking about a redesign and rethink of 
pretty much the entire language -- with list and generator 
comprehensions, for procedural programming the need for map and lambda 
goes away.  Reduce isn't directly replaced, of course, but a for-loop 
implementation (for procedural programming) is clearer, more powerful, 
more explicit, and possibly faster.

That said, I very much like the idea of putting map and filter in a 
functional module.  For applications like functional-style programming 
where map/etc are clearer, that keeps them in the library for efficient 
use, yet it leaves the native language with OO(g)WTDI [Only One (good) 
Way to Do It].

[1] -- lambda excepted.  I think it's kind of cute, in a baby-mammal 
kind of way.