Existential Types — Make OOP Great Again!

on YouTube ↗38m

" summary

Existential types are encoded as abstract type members so a Unix-style API can hide raw ints for file descriptors and force creation via open, eliminating forged 42 errors; UI examples use path-dependent types to model container/tabs state without unsafe wildcards (requires a trait work‑around because the compiler rejects the straightforward case class pack); plotting examples show type families that remove casts between Plot and Dataset; finally tagless DSLs give extensible interpreters.

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" chapters (34)

1. 0:00Intro
2. 0:15Outline
3. 1:24Complexity
4. 1:45Modularization and generalization
5. 3:271.2 Square of abstraction
6. 3:47Value parameters
7. 4:42Scala square of abstraction (2)
8. 5:48Scala square of abstraction (3)
9. 7:53Scala square of abstraction (4)
10. 9:10Scala square of abstraction (5)
11. 10:24Use cases
12. 10:35Scala interface for nix files API
13. 11:51Hiding the File type
14. 13:21Why is it different from using an opaque type?
15. 14:23Encapsulation - summary
16. 14:52User interface Component
17. 15:19Counter component
18. 15:43Container component
19. 19:45Redesign Component with abstract type members
20. 22:17Tabs - view implementation
21. 22:32Modularization - summary
22. 24:36Naive solution - XYPlot
23. 25:54Solution with abstract type members
24. 26:38Type families - summary
25. 27:34Questions?
26. 29:10Evaluating programs
27. 29:40Generalizing interpreters
28. 30:02Alternative encoding: language definition
29. 30:47Alternative encoding: evaluation interpreter
30. 31:15Alternative encoding: interpreting programs
31. 31:48Finally tagless encoding - extensibility
32. 33:23Type parameters vs type members (1)
33. 34:33Finally tagless encoding - summary
34. 36:05Tabs component implementation

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