It's apples and oranges. The type system in Kotlin is integrated into the language. TypeScript is a preprocessor for JavaScript that isn't allowed to change the

It's apples and oranges. The type system in Kotlin is integrated into the language. TypeScript is a preprocessor for JavaScript that isn't allowed to change the JavaScript language, or have any runtime. The "as Foo" construct is for you to tell TS that you know better than it, or that you deliberately want to bypass the type system. You can have a runtime check, but you have to write the code yourself (a type predicate), because TS doesn't write or change any JavaScript*, it just type-checks it. I've certainly worked in new codebases where a relatively simple subset of TS types were used. Even then there were a few places the crazy type system was helpful to have. For example, we enforced that the names of the properties in the global configuration object weren't allowed to have consecutive uppercase letters! (* with minor exceptions like transpiling for new JS features)