Consider deprecating "stdin" / "stdout" / "stderr" in favor of "askStdin" / "askStdout" / "askStderr" about rio

[akhra]

Not really sure if this is worth it, because it would mean that everyone would need to have stdio handles in their reader environment.

Hm. We could provide a StdHandles type and smart constructor(s), which would at least streamline this.

We... could... bake that into RIO, making it secretly ReaderT env (ReaderT StdHandles IO).

The latter idea is almost certainly horrifically terrible. Unless we newtype it as StdRIO so it's optional. Then just regular terrible?

[snoyberg]

Personally, I think this is too far into the "not common practice" area, at least for now.

[mgsloan]

Yup, reasonable!