Lambda, map, filter

lambda args: expr — an unnamed function for short one-liners. Don't write multi-line lambdas; define a real function instead.

The Pythonic preference

[f(x) for x in seq] is usually clearer than list(map(f, seq)). But map/filter shine when passing functions around or chaining.

Where you'll really use lambdas

sorted(items, key=lambda x: x.name) — providing a key function inline.

Try it

1. Sort [("Ada", 30), ("Bob", 25)] by age.
2. Use filter to keep only positive numbers from [-2, -1, 0, 1, 2].