I'm wondering if there's a reason that there's no `first(iterable)` in the Python built-in functions, somewhat similar to `any(iterable)` and `all(iterable)` (it may be tucked in a stdlib module somewhere, but I don't see it in `itertools`). `first` would perform a short-circuit generator evaluation so that unnecessary (and a potentially infinite number of) operations can be avoided; i.e.

```
def identity(item):
    return item

def first(iterable, predicate=identity):
    for item in iterable:
        if predicate(item):
            return item
    raise ValueError('No satisfactory value found')

```

This way you can express things like:

```
denominators = (2, 3, 4, 5)
lcd = first(i for i in itertools.count(1)
    if all(i % denominators == 0 for denominator in denominators))

```

Clearly you can't do `list(generator)[0]` in that case, since the generator doesn't terminate.

Or if you have a bunch of regexes to match against (useful when they all have the same `groupdict` interface):

```
match = first(regex.match(big_text) for regex in regexes)

```

You save a lot of unnecessary processing by avoiding `list(generator)[0]` and short-circuiting on a positive match.