well, it'd be more like (fold op . map f . filter p . zip) l1 l2 Which I think is very understandable as long as you're familiar with what all of them do. Whi

well, it'd be more like (fold op . map f . filter p . zip) l1 l2 Which I think is very understandable as long as you're familiar with what all of them do. Which you become, very quickly.