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Comment by contravariant | Hacker News Reader

Yeah I get that it can be useful, but I just don't like ending a loop in two different ways. It just seems too easy to end up writing something like:

    for x in sorted_list:
        if x == to_find:
            print("found")
            break # we've found a match
        elif to_find > x:
            break # match is not possible
    else:
        print("not found)

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Funny, I actually like for-else because it can simplify loop exits.

First of all, the core of a linear search loop always has two exits: the break and the normal (unsuccessful) loop exit.

But in a lookup-or-insert pattern, a regular for loop has two possible states that the system can be in at the end of the loop. With a for-else loop, you can put the or-insert part into the else block, so that there is a simpler invariant: after the loop construct, the element always exists and has been found.

I was honestly surprised by all the negativity in this thread. To offer an alternative opinion, there have been plenty of times when I missed having for-else while writing C.

I feel the same way. For-else is one of those things that make me miss Python when I'm working in another language, alongside things like list/set/dict comprehensions, Python's object model and it's way of dealing with generators and iteration.

") # There you go

Also, nice counterexample.

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