Category Theory for Programmers: Chapter 7 - Functors (by Example)

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[@markhathaway9456]

"mapping between categories" is the most succinct description and after that all the difficulty was in Haskell's lack of familiar code and C++ lack of *

[@code_report]

At 2:20 I say "A functor just defines" ... I meant "A typeclass just defines"

[@chewbaccarampage]

What software are you using for your slides? It's very slick.

[@Cristian_DG]

you can rewrite map using this type signature: map :: (a -> b) -> ([]) a -> ([]) b and this is valid in haskell

[@RogasTV]

The composability of functors is an interesting idea. You could have a function a -> b and map it not only on “containered” a and b (e.g. [a], [b]) but on “containered” and “maybed” a and b ([Maybe a], [Maybe b]). Great work with the videos! This is exactly what I needed to advance my category theory explorations.

[@Swangorapofficial]

Wow this is super useful I’m new into coding and this is excellent!

[@matthewhammond859]

I'm completely new to programming, thanks for introducing me to this content, even though at this time a lot of it is going over my head.

[@japedr]

In 10:17, is there a reason why fmap is not static? Great work as always.

[@EngineerNick]

Thankyou this is a great explanation :) I feel like I have met the need for functors pretty frequently, but for complex types it often feels impractical to implement the fmap function so i write some kind of spaghetti instead. Also, once you write fmap.... it's not always clear how to leverage it in a language like python where partial functions are an inconvenience and my code is riddled with mutable types anyway. *sad imperative noises*