Zod is by far the most ergonomic way to express those ideas in TypeScript these days. I miss it when writing code in other languages.

The friction with the rest of the ecosystem is real, though. Most code out there expects you to handle errors with exceptions.

I get the impression that polymorphic return types could get in the way of JSC/V8/SpiderMonkey's JIT, but I haven't measured it and I'm not sure of the actual impact on hot and cold paths. Same for all the allocations caused by custom Option<T>/Result<T,E> implementations.

I think using Zod at the edge (with branded types and whatnot), while keeping return types as T/Promise<T> to keep a sane relationship with the ecosystem is a good middle ground.