Question

I try to define a function as short as possible, and the function to return True if test is always true, and false if there is some value for which it is false. I tried so:

def res(v): for d in List: return True if v.test(d) else: pass

It does not work. How to define such a function ?

I want to define it on only one line.

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Answer 1

What about:

res = lambda x: all(test(v) for v in x) 

Or

res = lambda x: all(map(test, x))

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As mentionned by Vladimir in the comments, your test is actually a method of an object called v, so it should actually be:

lambda v: all(map(v.test, List)) # You should not use List as a variable name!

You probably would like to pass the List as an argument too though.

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Have a look at the documentation for the all method, the one for the map method and lambda functions.