How to get that output from a generic list in python

Question

is there a way to get this output:

a
b
aa
ab
ba
bb
aaa
aab...

using a list like this:

List = ["a","b"]

the method below can't be used because the output should be infinite

for i in List:
   print(i)
for i in List:
   for k in List:
      print (i+k)
for i in List:
   for k in List:
      for j in List:
         print(i+k+j)
#etc.

Answer 1

You could define a generator function using itertools.product :

>>> import itertools
>>> def infinite_products(chars):
...     for repeat in itertools.count(1):
...         for result in itertools.product(chars, repeat=repeat):
...             yield ''.join(result)
...
>>> for result in infinite_products("ab"):
...     print(result)
...
a
b
aa
ab
ba
bb
aaa
aab
aba
abb
baa
bab
bba
bbb
aaaa
aaab
aaba
aabb
abaa
abab
abba
abbb
baaa
baab
baba
babb
bbaa
bbab
bbba
bbbb
aaaaa
aaaab
aaaba
...