ts-pattern

I love how far Java has come. I still prefer TypeScript since I do a lot of frontend work and prefer to use the same language across the stack. With the said, you can do exhaustive pattern matching in TypeScript! https://github.com/gvergnaud/ts-pattern

I would highly recommend the ts-pattern [1] library if you find yourself wanting exhaustive switch statements! The syntax is a bit noiser than case statements in simple cases, but I find it less awkward for exhaustive pattern matching and much harder to shoot yourself in the foot with. Once you get familiar with it, it can trim down a /lot/ of more complicated logic too. It also makes match expressions an expression rather than a statement, so it can replace awkward terenaries. And it has no transitive dependencies! [1]: https://github.com/gvergnaud/ts-pattern

You might like ts-pattern https://github.com/gvergnaud/ts-pattern

Yeah, that can be annoying. Until pattern matching makes it into JS, the main way people deal with this is to use a library. For example, ts-pattern lets you stick `.exhaustive()` at the end of a match call and I believe you get the error at typechecking time, not runtime. https://github.com/gvergnaud/ts-pattern

ts-pattern has been a decent band-aid for the lack of native pattern matching, but obviously has downsides that could be avoided if it was built into the language. https://github.com/gvergnaud/ts-pattern

With how powerful the type system is you can implement pattern matching via a library pretty convincingly, https://github.com/gvergnaud/ts-pattern is definitely the go-to. That being said pattern matching is hardly a requirement for being ok for implementing compilers.

I'm quite fond of this library for pattern matching; it's a staple in all my new projects. https://github.com/gvergnaud/ts-pattern

I'm not aware of any related to testing, but perhaps you could use something like this in tandem with some tests to pull it off? https://github.com/gvergnaud/ts-pattern

> TypeScript doesn't even come with ADTs You still can use them [0]. > proper pattern matching [1] is pretty good. [0] https://itnext.io/practical-introduction-to-algebraic-dataty... [1] https://github.com/gvergnaud/ts-pattern

The tc39 pattern matching proposal seems to have some renewed energy with new champions (including from the typescript team) and syntax proposals: https://github.com/tc39/proposal-pattern-matching Also there has been movement in the user land space with libraries like ts-pattern that make use of new features in typescript 4.x to provide basically the full pattern matching experience: https://github.com/gvergnaud/ts-pattern