> From practical point of view, I fail to see the difference between explicitly passing strings and adding the `can Use Strings` signature -- when you want add passing extra context to existing functions, you still need to go to all of them and add the appropriate plumbing.

Couldn't the plumbing be reduced significantly through type inference? I.e. the function that invokes an effect will need the signature, the callers higher up the chain won't.

Also, even if you had to adapt all the signatures, at least you wouldn't have to adjust the call sites themselves to pass in the context every single time.