Re: [Caml-list] Are implicit modules too implicit?

[Leo White <leo@lpw25.net>]

> Currently I'm in a Scala project where there are a number of implicits,
> and the question which implicit is actually used is a real one.

It is worth bearing in mind that the resolution of implicits in Scala is much more
complicated than the rules for modular implicits. Scala has very complex scoping
rules for implicits, whereas modular implicits just uses lexical scope. Scala also
allows ambiguous implicits to be resolved according to a complex set of overloading
rules, whereas modular implicits always gives an error for ambiguous implicits.

> Having
> support in Merlin is good, but I think there could also be support in
> the compiler. What about adding a warning "implicit X is resolved
> as ..." which can be used for tracing the resolution during the build?

I suspect a warning would be a bit too noisy to read usefully, but it should be
quite easy to have the compiler print the source of the program with all the implicit
parameters passed explicitly (so [show 5] would become [show {Show_int} 5]). It
wouldn't be able to keep the indentation of the source, but it should still be easy
to find the implicit you're interested in.

Regards,

Leo