It’s the mapping itself that can be composed with transducers. Where before you had pipelines of map/filter/whatever, now you have a single function representin

It’s the mapping itself that can be composed with transducers. Where before you had pipelines of map/filter/whatever, now you have a single function representing the sequence operations, which can be used for any kind of sequence (a list in memory, or items coming in over a channel or message queue) item by item.