I created a Result style interface in Typescript and made the decisions to fix the Error to a single type for this very reason.

Result<T> instead of Result<T,E> so that it was easier to compose.

This made Kleisli composition easier since I don't have to worry about mismatched types on the Error.

You can see the code at https://github.com/brennancheung/wasmtalk/blob/master/src/fp...