map/filter/reduce/lambda opinions and background unscientific mini-survey

[Jamey Cribbs]

Tom Anderson wrote:
> So, if you're a pythonista who loves map and lambda, and disagrees with 
> Guido, what's your background? Functional or not?

I have no functional language background.  Until recently, I had no use 
for programming "expression to be evaluated later" or "deferred 
expressions" or whatever else they are being called.

Where I came to see the awesomeness of "deferred expressions" was a few 
months ago when I started a major rewrite of KirbyBase for Ruby.  I 
wanted to make the Ruby version of KirbyBase take advantage of the 
strengths of the language.  Another Ruby programmer, Hal Fulton, was 
helping me by constantly pushing me to make KirbyBase more Ruby-ish. 
One thing he kept pushing was to be able to specify select querys using 
Ruby's "deferred expression" mechanism, code blocks (before anyone 
starts yelling, I know that Ruby code blocks are *much* more than just 
"deferred expressions"; I'm just using that descriptor here for the sake 
of this discussion).

Code blocks allow you to wrap up any Ruby code and pass it to a method 
and have it executed within that method.  It is more powerful than 
lambda, because you can have multiple statements in the code block and 
you can do assignment within the code block.  This allowed me to rewrite 
KirbyBase so that you can do a select like this:

plane_tbl.select { |r| r.country == 'USA' and r.speed > 350 }

Now, this is cool, but you can do this using lambda in Python.  Where 
Ruby code blocks really shine is that you can also do this:

plane_tbl.update {|r| r.name == 'P-51'}.set {|r|
     r.speed = 405
     r.range = 1210
}

I have one code block that I pass to the update method which says 
"Select all planes with name equal to P-51".  Then, I pass a code block 
to the set method which assigns new values to the speed and range fields 
for those records (i.e. P-51) that were selected in the update method. 
This is something you can't do with lambda.

Now, I think I can duplicate the same functionality of Ruby code blocks 
by using Python functions, but it is not going to be as pretty.

So, even though lambda is not as powerful as Ruby code blocks, I was 
still bummed to read that it is going away, because it is better than 
nothing.

Hopefully, Guido will reconsider or, even better, give us something even 
more powerful.

Jamey Cribbs