How to be polymorphic in Scala

on YouTube ↗45m

" summary

Explains concrete Scala features: type classes implemented via implicits with examples for Int and List, a Show instance that either prints numbers or bars, and compiler errors when instances are missing; shows implicit conversions used to extend syntax (custom ternary-like operator, complex number + overload) and how variance, higher-kinded types and predicative limits behave. Demonstrates trait mixins for per-instance behavior, notes compile-time dispatch and runtime performance tradeoffs (slower compilation but zero runtime magic).

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" chapters (12)

1. 0:00Polymorphism introduction
2. 1:20Parametric polymorphism
3. 5:17Higher-rank polymorphism
4. 7:24Variance in Scala
5. 13:54Traits and roles
6. 17:56Operator overloading
7. 21:11Type casting
8. 24:02Syntax extension
9. 28:17Type Class in Scala
10. 35:27Type Class practice
11. 37:37Comparison with JavaScript
12. 41:15Conclusion

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