To summarize:

• Stream transformations are built using pulls.

• All streams can be converted to pulls, and some pulls can be converted to streams.

• Pulls can output elements and return a result.

• Pulls are monads — they can be composed using flatMap.

You’re now well equipped to be creative with your own custom pulls. If you need more inspiration, take a look at the following posts.

• Gavin Bisesi’s excellent gist explores a more advanced usage of pulls with effects as well as some gotchas of working with effect evaluation.

• Have a look at the fs2 codebase to see how its own pipes and are written.

• Read Fabio Labella’s explanation on Gitter to learn more about the reasoning behind pulls.

Credits

Many thanks to Fabio Labella, Gavin Bisesi, Michael Pilquist and Adam Rosien for giving this a reassuring read.