suggestion for an additional for-loop structure.

hybrid_loop.py

#######################################
# suggestion for an additional for-loop structure.
#######################################

for x in y while condition:
    do_stuff()

# as syntax sugar for:

for x in y:
    if condition:
        do_stuff()
    else:
        break

# I want a way to loop through an iterable, but stop as soon as a condition
# becomes False. So, essentially I want a hybrid of a for and a while loop.

# Uses for stopping iteration once condition becomes False:
#   - Useful for saving computation in cases where you know that, once the
#     condition is False, it won't evaluate to True for any more of the elements in
#     the iterable.
#   - Especially important if the contents of the for block are
#     computationally expensive.
#   - Problem is compounded if you have a very long iterable.

# This could be accompanied by an additional list comprehension and generator
# expression structure:

l = [x for x in y while condition]  
g = (x for x in y while condition)

# this syntax would be sugar for the more clunky:

l = []
for x in y:
    if condition:
        l.append(x)
    else:
        break