Is there an expression for an infinite iterator?
itertools provides three infinite iterators:
count(start=0, step=1): 0, 1, 2, 3, 4, ...cycle(p): p[0], p[1], ..., p[-1], p[0], ...repeat(x, times=∞): x, x, x, x, ...
I don't know of any others in the standard library.
Since you asked for a one-liner:
__import__("itertools").count()
for x in iter(int, 1): pass- Two-argument
iter= zero-argument callable + sentinel value int()always returns0
Therefore, iter(int, 1) is an infinite iterator. There are obviously a huge number of variations on this particular theme (especially once you add lambda into the mix). One variant of particular note is iter(f, object()), as using a freshly created object as the sentinel value almost guarantees an infinite iterator regardless of the callable used as the first argument.
you can iterate over a callable returning a constant always different than iter()'s sentinel
g1=iter(lambda:0, 1)