exists in python an equivalent to Haskell's mapM_ function?
example ("print()" is here only a placeholder for every function with Signature: a -> None):
#pseudo code!!!
map (lambda x: print(x), [1,2,3])
like in Haskell:
mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()
> mapM_ print [1,2]
> 1
> 2
map just creates a lazy iterator. You would have to consume such an iterator (e.g. by calling list on it) in order to harvest the side-effects. Since that wastes memory (as do other collection constructors), the recommended consume recipe uses a zero size collections.deque:
from collections import deque
def consume(iterator):
deque(iterator, maxlen=0)
Now, you can consume an iterator with a small memory footprint:
lazy = map(print, [1,2,3]) # using lambda here defeats the purpose of functions
consume(lazy)
But TMK this provides little advantage over a simple loop:
for x in [1, 2, 3]:
print(x)
