Subtyping is Overrated
summary
Claim is that subtyping is overrated: implicit runtime subtyping (JavaScript, Java, C#) forces dynamic dispatch and small but real overheads, while ML/Haskell/Rust style approaches avoid them. Demonstrations compare prototype lookup cost versus a compiler match on algebraic data types, show Flow/TypeScript examples of subtype relations, and describe alternatives: Haskell type classes and Rust box traits (explicit vtable boxing) to regain dynamism. Result: same abstractions with less default runtime cost.
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chapters (13)
- 0:00Introduction
- 1:00Caleb Meredith
- 2:40Plants vs Animals
- 3:55Dynamic vs Static
- 8:34What is Subtyping
- 11:49Why is Subtyping Popular
- 13:07Subtyping Adds Overhead
- 13:47How Subtyping Works
- 14:45JavaScript
- 15:17Overhead
- 16:51Supertype
- 18:08Type classes
- 20:55Outro
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