First-class global macros

[Kodiologist]

This pull request partly fulfills #1467, by testing and documenting introspection that's possible via _hy_macros, and removing some functions and macros that are made redundant by these features. _hy_macros only provides access to global macros, so the missing part is support for local macros. That I expect to require implementing new features, so I'm leaving it for another PR.

[scauligi]

Hold on, I'm confused. Are we considering _hy_macros as part of Hy's public API now? I thought it was just internal?
Also I see no reason to remove doc just yet, even if we are officially exposing _hy_macros, since using doc is much more ergonomic than pulling mangled keys out of _hy_macros.

[Kodiologist]

Are we considering _hy_macros as part of Hy's public API now? I thought it was just internal?

Right, it was internal, but by documenting it, I'm making it public. Making what we already have public seemed like a more straightforward way to provide these features than to add another interface.

I see no reason to remove doc just yet, even if we are officially exposing _hy_macros, since using doc is much more ergonomic than pulling mangled keys out of _hy_macros.

It is, yes, but that seems more like something for Hyrule than something to keep as a core macro.

[scauligi]

I disagree wrt doc, I feel like it's important enough that it still belongs as part of Hy's core; it's the analogue of Python's help being a builtin rather than a function imported from the stdlib or asking the user to print(function.__doc__).

Otherwise, for other removals like delmacro, is the intention to have a set of macro-managing macros eventually in Hyrule?

[Kodiologist]

I disagree wrt doc, I feel like it's important enough that it still belongs as part of Hy's core; it's the analogue of Python's help

Thing is, Hy's analog of Python's help is help. All the actual logic of doc is finding the named macro. Once it has the macro, it just calls help. So if you think (help (get _hy_macros (hy.mangle "macroname"))) is too inconvenient, what if we provided (get-macro macroname)? Then you could say (help (get-macro macroname)). And it would be useful for other things; you could also say (del (get-macro macroname)), for example.

for other removals like delmacro, is the intention to have a set of macro-managing macros eventually in Hyrule?

It's the sort of thing one could add to Hyrule, but I have no motivation to do so. I don't see myself manipulating the macro system like this a huge amount.

[scauligi]

My preference is still to keep doc, but I'm willing to settle for (help (get-macro ...)).
I do agree that regardless, get-macro seems like a good general utility to have.

[Kodiologist]

Okay, I'll take a stab at adding get-macro to this PR.

[Kodiologist]

get-macro turns out to be harder to get right than I expected, and I don't really want to work out all the subtleties right now, so I just undid the removal of doc from this PR. Look good?

[scauligi]

Yup, otherwise looks fine 👍