The way JavaScript handles async is pretty close to monadic. Error handling via the local equivalent of Maybe / Either is monadic. Tuples are monadic. Sequences can be monadic. Etc. Some languages have a flexible enough type system to expose this (like Haskell), some don't. Some like Rust generally don't expose monads to the type system, but their users are aware enough of the shared monadic structure that you can see it reflected in the naming conventions for functions that do essentially the same thing (in a monadic sense) but for different structures.