Re:The Next Step for Generics
by dragonwriter on Wednesday June 17, 2020 @11:15AM
(#23552415)
> If you design your functions in a way that that function will never receive an array, you dont have to test for it. And if some idiot tries one day, it should error very loudly that something is wrong.
That's naïve. Unless you code extra defensively (which is the same type of overhead as excessive testing, and needs itself to be verified by testing), there's very little guarantee that type errors will result in loud failure consistently at the first point that the bad value is passed (because functions that don't do unnecessary work often pass their arguments along without doing a lot of work dependent on the very specific type.)
And, in any case, failing consistently at compile time (or, with a modern code editor, at writing time) with static type checking is better than failing at runtime, even if it is loud and consistent.
Of course things like mypy and TypeScript (especially, in the latter case, because it powers tools that work pretty well when the actual immediate source is plain JS, or JS with JSDoc comments from which type information can be extracted, when consuming libraries with TS typings) mean that some popular dynamic languages have static type checking available with more expressive type systems than a number of popular statically-typed languages.
That's naïve. Unless you code extra defensively (which is the same type of overhead as excessive testing, and needs itself to be verified by testing), there's very little guarantee that type errors will result in loud failure consistently at the first point that the bad value is passed (because functions that don't do unnecessary work often pass their arguments along without doing a lot of work dependent on the very specific type.)
And, in any case, failing consistently at compile time (or, with a modern code editor, at writing time) with static type checking is better than failing at runtime, even if it is loud and consistent.
Of course things like mypy and TypeScript (especially, in the latter case, because it powers tools that work pretty well when the actual immediate source is plain JS, or JS with JSDoc comments from which type information can be extracted, when consuming libraries with TS typings) mean that some popular dynamic languages have static type checking available with more expressive type systems than a number of popular statically-typed languages.