Expose structure of `ProcessConfig` from internal module.

[mpickering]

I wanted to write a wrapper of runProcess which would print out the command which was going to run before running it. However, the only way I have display a ProcessConfig is using the Show instance which prints out a lot more information (including full environment).

Ideally it would be good to expose the structure of ProcessConfig via the internal module (so I can write the function myself).

[snoyberg]

I don't see a problem with that. @tomjaguarpaw any thoughts?

[tomjaguarpaw]

I'll defer to whatever is your preference, Michael.

I personally don't know immediately how to satisfy the request whilst being sure I'm not violating a desirable invariant or abstraction layer of this library, so it would be very low down my priority queue of Haskell-things-to-work-on.

That said I won't stand in you and @mpickering's way if you want to put together a change that tackles this issue. I'm also open to further discussion about it in case I've missed a reason why it's not easy enough for users to work around (for example by defining a wrapper type for ProcessConfig).

[tomjaguarpaw]

Oh, actually I think I misunderstood the request. I'm in support of exposing any internals from modules named .Internal as long as users know that they can't rely on their behavior or stability.

So I don't see a problem with this either.

[tomjaguarpaw]

Released here: https://hackage.haskell.org/package/typed-process-0.2.11.0