Support literal true and false types

[danog]

This PR adds support for literal true and false types.

[romm]

Hi @danog thank you very much!

I wanted to add some things but I can't write to the repository because it is owned by an organization, see https://github.community/t/how-can-we-enable-allow-edits-from-maintainers-by-default/2847 ; could you add me as a maintainer to this very repository, as it was done there?

Thanks!

[danog]

Done!
Though I also wouldn't have minded if you closed this PR and did a manual merge on a feature branch of this repo :)

[romm]

Perfect, thanks!

Just pushed, I'll let you some time to review the changes and tell me if everything is ok by your side. 🙂

[danog]

Looks great, thanks!
Can I haz a tag after the merge? :3

[romm]

Actually I missed one thing: TrueType and FalseType should both be implementing ScalarType; missing methods should be implemented and tested as well. Do you want to try to do it by yourself? Otherwise I'll take time to do it, no worries.

Anyway when it's ready I'll gladly publish a new release, that is well deserved!

[danog]

I'll do it tomorrow, no worries!

[danog]

Now that I took a look at it, maybe extending ScalarType isn't such a good idea after all: like with the literal null type, which doesn't extend ScalarType, we want to treat only the literal null case, without handling or supporting casts, which would make little sense given that we explicitly specified a literal type.

[romm]

I understand your concern; null is not a scalar because… well it's not a scalar type that's all. Concerning true and false, in order to be consistent with the BooleanType we need to allow them to accept values like 1 or 0. I made this choice at the beginning of the project, it was already challenged in #3 and will be part of a major change in a next release.

In the meantime, we need to be consistent with the existing features. 🙂

[romm]

Hi @danog I changed to boolean types to be handled as scalar; I also changed some things to be more consistent with other "value types" (FloatValueType / IntegerValueType / StringValueType).

Anyway, thanks for the original work!

[romm]

There you go sir 🙂

https://github.com/CuyZ/Valinor/releases/tag/0.8.0

[danog]

Yay, thanks, almost forgot about this PR :)