Question

primes = [2,3,5,7..] (prime numbers)
map(lambda x:print(x),primes)

It does not print anything.
Why is that?
I’ve tried

sys.stdout.write(x)

too, but doesn’t work either.

Answer 1

Since lambda x: print(x) is a syntax error in Python < 3, I’m assuming Python 3. That means map returns a generator, meaning to get map to actually call the function on every element of a list, you need to iterate through the resultant generator.

Fortunately, this can be done easily:

list(map(lambda x:print(x),primes))

Oh, and you can get rid of the lambda too, if you like:

list(map(print,primes))

But, at that point you are better off with letting print handle it:

print(*primes, sep='\n')

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NOTE: I said earlier that '\n'.join would be a good idea. That is only true for a list of str’s.