The many shapes of Polymorphism

on YouTube ↗47m

" summary

Argues that which polymorphism a language supports actually changes code shape, comparing Java, Scala, OCaml, Haskell, Go and Rust and showing concrete scala snippets: a Money trait with Fiat and Metal, show/serialize/plus examples, and a web‑service duplication refactor. Demonstrates the adapter pattern to regain type safety, contrasts parametric (generics), subtype polymorphism (inheritance pitfalls, variance issues) and type classes (less boilerplate in Haskell, harder in Scala, cannot add types at runtime), and recommends learning multiple languages to see tradeoffs.

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" chapters (23)

1. 0:00Intro
2. 2:15Optical Illusion
3. 4:57Why do we use Types in programming languages?
4. 5:10A type system is a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute.'
5. 6:41The need for polymorphism
6. 9:32There are new discoveries in type systems
7. 11:01Hypothesis: the way the Polymorphism is used defines the shape of our code
8. 16:35Let's start working
9. 19:43Let's try (real) subtype polymorphism
10. 22:30We're mixing domain logic and behaviour
11. 25:02Adapter Pattern
12. 32:29Ad-Hoc polymorphism
13. 34:02Type class cannot provide new types at runtime
14. 35:00Mixing different types of polymorphism
15. 35:19Mix subtype polymorphism with generic
16. 35:42Mix generic polymorphism with ad-hoc?
17. 36:07Polyglot programming
18. 37:32Can type classes replace subtype polymorphism?
19. 39:55Are type classes only for Functional Programming language?
20. 41:13Addendum
21. 41:50Thank you for your time Feedback please!
22. 44:48Scala is a bridge from OOP to FP world
23. 46:04Type inference and subtypes

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