refactoring: Use tryJust instead of pattern guards

[sol]

Doing this first will give us a smaller diff for #70, hopefully putting us into a better position to make progress there.

This reduces the diff for #70 to essentially: sol@4c5d917

But ignoring #70 for a moment, I still think this is a reasonable improvement.

[tomjaguarpaw]

I found this a little hard to follow. Could you please rebase on https://github.com/tomjaguarpaw/typed-process/tree/terminateProcess for clarity? That makes each of the steps painfully obvious.

[sol]

I found this a little hard to follow. Could you please rebase on https://github.com/tomjaguarpaw/typed-process/tree/terminateProcess for clarity? That makes each of the steps painfully obvious.

done.

[tomjaguarpaw]

If find the tryJust and guard much harder to understand, actually, but I think my three commits are equally good for your purpose, @sol, are they not? Unless they're not, I intend to merge them in #72.

[sol]

Anything works for me. Closing in favor of #72.