[chc]

I find Python's list comprehensions mind-numbing in many simple cases, such as [x for x in xs if some_condition(x)] rather than just xs.filter(some_condition). We're repeating the variable name three times and zero of those times convey any useful information, and we don't find out until the very end of the line that the everything except "[", "]" and "some_condition" was ignorable.

And in cases where a data-deriving loop has so much going on directly in the loop body that it makes map/filter/reduce hard to read, there's very often some refactoring that would improve either version.

[jstimpfle]

This is the one case where python's list comprehension syntax isn't so efficient. Don't worry about it - be consistent and use it nevertheless. It doesn't matter much.

In the cases where x gets also transformed or you do some unpacking the syntax is very efficient and easy to read: [f(y) for x, y in items if g(x)]. Basically it's a poor man's relations programming (think databases). It's brilliant. (And definitely easier to read and write than the Haskell list comprehension syntax).