Languages should have opinionated interop features

A lesson we can derive from Rust’s error handling and async libraries, and Haskell’s effect system libraries, is that languages need to have opinionated (and efficient, flexible) interop features. If not and the language is flexible enough (with an expressive type system, and maybe also with metaprogramming features), users create their own solutions and the ecosystem gets fragmented. Consider error reporting. Without a convenient way of error handling built into the language, a library for SQLite access, another one for HTTP requests, and another one for TCP connections will potentially use different error reporting libraries and cause friction. A similar thing commonly happens today with Rust async libraries and Haskell effect system libraries, which create a whole ecosystem of libraries that just do same things (e.g. SQLite access) but using different async, error handling, or effect system libraries. The worst outcome here is entire sets of libraries that can’t be used together.…