pull-streams: there is a module for that!

how can I achieve 1:many and many:1 transforms?

use pull(pull.map(mapToArray), pull.flatten())
use pull-through
use pull-flatmap

how do I interop with node streams? are there any caveats?

use stream-to-pull-stream back pressure will still work correctly. make sure you use toPull.source(readable) toPull.sink(writable) or toPull.duplex(duplex).

is there a way I can push to a pull stream?

generally, avoid doing this if you can because you'll loose back pressure, but if you must

use pull-pushable

can i apply a async function over pull-stream input?

use pull-paramap order will be preserved.

I need to return a stream immediately, but need to do something async first, how?

use pull-defer
or pull-cont

can I concat two pull-streams

yes.

use pull-cat

How do I fork a pull-stream?

eg: if there's an error, I want to stream to stderr, otherwise stream to stdout