Alejandro Serrano Mena on Why Functors and Applicatives Compose but Monads Don't

Alejandro Serrano Mena explains the mathematical and practical reasons why functors and applicatives compose while monads do not.

In this presentation, Alejandro is going to talk about one of the many kinds of composition available in Haskell, namely "functor composition": for any two functors we can create a new one. Some functors, such as applicatives and monads, have additional structure. Interestingly, applicatives can be composed to get a new applicative, but the same does not happen for monads. This has important implications: since monads do not compose, we need something else. Join us for a stimulating evening discussion with a true scholar of functional programming. This talk will be especially appropriate for beginners to Haskell who would like a better understanding of one of its fundamental concepts: composition. Alejandro is a senior software engineer at 47 Degrees, devoting his time to training and open source around Haskell. Before that, he held several positions at Utrecht University, from which he obtained a Ph.D. on a topic related to compiling functional languages. He has wide experience, as a speaker and lecturer, in introducing functional concepts and is the author of the books, "Practical Haskell" and "The Book of Monads". Slides available here: dropbox.com/s/1j828vngpm0yhja/fp-berlin-2020.pdf?dl=0 This virtual talk was brought to you by the Berlin Functional Programming Group. Join us on Meetup: meetup.com/Berlin-Functional-Programming-Group/ Follow us on Twitter: twitter.com/BerlinFPGroup Buy a T-shirt: teespring.com/berlin-fp-group Support us on Patreon: patreon.com/bfpg