Download for much higher quality version of the slides. Start with expression ma flatMap f and keep refactoring it by applying each of ⑧ rewrite rules in turn, until you get back to ma flatMap f.

1. Scala Functional Programming Combinators Code Kata
start with expression ma flatMap f and keep refactoring it
by applying each of ⑧ rewrite rules in turn
until you get back to ma flatMap f
@philip_schwarzslides by https://www.slideshare.net/pjschwarz

3. Rewrite Rules
① flatmap can be defined in terms of map and flatten
② map can be defined in terms of flatMap and pure
③ flatten can be defined in terms of flatMap and identity
④ chained flatMaps are equivalent to nested flatMaps (flatMap associativity law)
⑤ Kleisli composition can be defined in terms of flatMap (apply this the other way around)
⑥ the identity function can be defined in terms of flatten and pure
⑦ pure followed by flatten cancel each other out
⑧ pure is the identity function for Kleisli composition, so f >=> pure is the same as f

5. Only half-serious, of course.
But you may find it useful to work through the refactorings to
improve your understanding of various combinators.
And if you can’t be asked to type it all out, I made a gist for you
@philip_schwarz
https://gist.github.com/philipschwarz/a677eaa7ccc87d54673226f307b3fdb5