New Validation type

[gusty]

I would like to swap the type parameters order, so instead of Validation<'TError, 'T> we define it like Validation<'T, 'TError>.

Also we could change the field names to Okay and Errors, the latter gives us a hint that it's about accumulative validation.

This is, of course for F#+ 2.0

[wallymathieu]

Interesting suggestion. Could we do it in such a way that users of the lib doesn't get confused? I'm thinking about having it in a module that you would have to open, and putting a deprecation notice on the old one?

[gusty]

Yes, we have to think about it.
Anyways when the moment comes, I'm sure this won't be the sole type with such a breaking change.
We can then decide on which strategy.