Well looking at the form the other operations (map, reduce, filter, etc..) are they usually describe what is being done to the source as a way to describe the o

Well looking at the form the other operations (map, reduce, filter, etc..) are they usually describe what is being done to the source as a way to describe the output. As opposed to just describing the outcome. That being said there are some weird ones like "some" or "every". Regardless though some other well known FP languages use flatten so it lowers the barrier to entry on the API for people familiar with them.