<p>I would want to do something like:</p>

<pre><code>&gt;&gt;&gt; lst = [1, 2, 3, 4, 5]
&gt;&gt;&gt; lst.find(lambda x: x % 2 == 0)
2
&gt;&gt;&gt; lst.findall(lambda x: x % 2 == 0)
[2, 4]
</code></pre>

<p>Is there anything nearing such behavior in Python's standard libraries?</p>

<p>I know it's very easy to roll-your-own here, but I'm looking for a more standard way.</p>

You can use the filter method:
```
```
>>> lst = [1, 2, 3, 4, 5]
>>> filter(lambda x: x % 2 == 0, lst)
[2, 4]
```
```
or a list comprehension:
```
```
>>> lst = [1, 2, 3, 4, 5]
>>> [x for x in lst if x %2 == 0]
[2, 4]
```
```
to find a single element, you could try:
```
```
>>> next(x for x in lst if x % 2 == 0)
2
```
```
Though that would throw an exception if nothing matches, so you'd probably want to wrap it in a try/catch.  The () brackets make this a generator expression rather than a list comprehension.
Personally though I'd just use the regular filter/comprehension and take the first element (if there is one).
These raise an exception if nothing is found
```
```
filter(lambda x: x % 2 == 0, lst)[0]
[x for x in lst if x %2 == 0][0]
```
```
These return empty lists
```
```
filter(lambda x: x % 2 == 0, lst)[:1]
[x for x in lst if x %2 == 0][:1]
```
```