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1. That's a horrible description of unsoundness; you're making it sound like incompleteness! 2. What I meant to ask was: what does satvikpendem mean by "JS is
by creata 4y ago
1. That's a horrible description of unsoundness; you're making it sound like incompleteness!
2. What I meant to ask was: what does satvikpendem mean by "JS is unsound"? It's a dynamically typed language, so they can't be talking about soundness in the type system...
- orta 4y agoI did a bit of a writeup on the gaps in soundness for TypeScript in the docs, https://www.typescriptlang.org/play?strictFunctionTypes=false#example/soundness https://www.typescriptlang.org/play?strictFunctionTypes=fals...
- satvikpendem 4y agoI should clarify, the JS type system is unsound, and because JS is valid TS, TS is by extension also unsound. Not sure why you'd think a dynamically typed language cannot be unsound, it still has types, they're just not static.
- creata 4y agoDefine soundness. Here's something close to the definitions that I've seen: > The central result we wish to have for a given type-system is called soundness. It says this. Suppose we are given an expression (or program) e. We type-check it and conclude that its type is t. When we run e, let us say we obtain the value v. Then v will also have type t. - https://papl.cs.brown.edu/2014/safety-soundness.html https://papl.cs.brown.edu/2014/safety-soundness.html This only makes sense in the context of static types afaict, because you do not "typecheck an expression" in a dynamically typed language.
- satvikpendem 4y agoTypes can be checked at runtime too, not just compile time. A language is sound if all types, even at runtime, are what they say they are. Zod for TypeScript is one example of checking this at runtime, although it's not fully safe either.