The functionality of filter and map is the same as list comprehensions, so I don't think there's much loss there. I've never found a use for reduce in any program I've devised, and lambda is rather un-pythonic.
This said, I wish Python had some syntactic sugar for:
def anon(...):
# code
function(anon) Perhaps something like:
Where 'keyword could be something like "do" or "use".