converting boolean filter function to lambda

[Ian Kelly]

On Thu, Jun 25, 2015 at 9:59 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
> I have the following function:
>
> def phone_found(p):
>   for c in contacts:
>     if p in c:
>       return True
>   return False
>
> with the following test data:
>
> contacts = ['672.891.7280 x999', '291.792.9000 x111']
> main = ['291.792.9001', '291.792.9000']
>
> which works:
>
> filter(phone_found, main)
> # ['291.792.9000']
>
> My attempt at a lambda function fails:
>
> filter(lambda p: (p in c for c in contacts), main)
> # ['291.792.9001', '291.792.9000']
>
> Besides using a lambda ;) , what have I done wrong?

The lambda returns a generator, not a boolean. All generators are truthy.

I think you want this instead:

filter(lambda p: any(p in c for c in contacts), main)