Category Theory: You Already Know It

on YouTube ↗02h 41m

" summary

Explains how category theory concepts already appear in everyday coding using C# (and F#-style) examples: a banking micro-example filters suspicious account lines and sums Amount values using an Amount type and Status enum to avoid primitive obsession. Implements Maybe/Result types and functions like map/select, bind/SelectMany and flatten to compose partial or side-effecting steps, and demonstrates monoids (Amount addition with zero, string/list concat) with unit tests verifying identity and associativity.

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" chapters (13)

1. 0:00Category theory for devs
2. 12:11Category definition
3. 25:43Morphism composition
4. 38:21Abstraction vs info loss
5. 50:59Identity and isomorphism
6. 1:00:35Monoids in code
7. 1:12:58Side effects and composition
8. 1:22:14Q&A
9. 1:37:03Functors
10. 1:58:44Natural transformations
11. 2:05:20Monads: side effects
12. 2:31:59Monads: error handling
13. 2:38:22Summary

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