Christopher Subich wrote: > Carl Banks wrote: > > > > Christopher Subich wrote: > >>I've heard this said a couple times now -- how can listcomps not > >>completely replace map and filter? > > If you're doing heavy functional programming, listcomps are > > tremendously unwieldy compared to map et al. > > Interesting; could you post an example of this? Whenever I try to think > of that, I come up with unwieldly syntax for the functional case. In > purely functional code the results of map/filter/etc would probably be > directly used as arguments to other functions, which might make the > calls longer than I'd consider pretty. This is especially true with > lots of lambda-ing to declare temporary expressions.
I suspect you're misunderstanding what I mean by heavily functional. You appear to see maps and listcomps merely as a shortcut for a for loop. You're comparing the map shortcut and the listcomp shortcut and seeing which one's less verbose. In a mostly procedural program which uses functional constructs in isolation, listcomps are going to win most of those battles. 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. When your mind is focused on "applying a function to each member of this list and returning a list of the results" as opposed to "convenient shortcut to a for loop", map is going to be far superior to a listcomp. And when you're doing dozens and dozens of maps over a large purely functional program, you don't want to write out a listcomp every single time you want to do it. -- CARL BANKS -- http://mail.python.org/mailman/listinfo/python-list
