load mathics.builtin.box

[mmatera]

This PR fixes some flakiness I found during the Definitions refactoring: mathics.builtin.box.* was not loaded during the startup.

[mmatera]

@rocky, please confirm to me that this was a mistake and that we have no good reasons to do not to load these modules.

[rocky]

@rocky, please confirm to me that this was a mistake and that we have no good reasons to do not to load these modules.

I think all of those are imported as a result of importing other builtins via Python import statements. Was there a particular Builtin that wasn't found?

Because this is slow and non-standard, we use the dynamic loading only when there the modules wouldn't have otherwise have been imported by using Python's normal import mechanism.

And that is yet another good reason why it is nice to separate top-level Builtins from the implementation and the boxing of those and the formatting - none of the things in the later category needs to be loaded in a non-standard way.

[mmatera]

@rocky, please confirm to me that this was a mistake and that we have no good reasons to do not to load these modules.

I think all of those are imported as a result of importing other builtins via Python import statements. Was there a particular Builtin that wasn't found?

Yes, all the built-in inside mathics.builtin.box are not loaded. I discovered this playing with the Definitions object.

Because this is slow and non-standard, we use the dynamic loading only when there the modules wouldn't have otherwise have been imported by using Python's normal import mechanism.

Indeed, at some point we need to thing about a better mechanism to load de built-in definitions. But it is a lot of work, and it just save a few seconds in the loading time.

And that is yet another good reason why it is nice to separate top-level Builtins from the implementation and the boxing of those and the formatting - none of the things in the later category needs to be loaded in a non-standard way.

OK, but again, that is another step. My idea, in the long term, is to put all the complex formatting stuff in external modules (like pymathics-asy or pymathics-matplotlib and keep in the core the essential infrastructure for evaluation and rule application. In any case, we still have a long trip until there.