The implementation is good enough for implementing extensible parsers,
elaborators and tactics, but there are a few TODOs
1- We should have a better story for standalone applications.
Most of them don't need `evalConst`, and the global table is
just initialization overhead.
2- The global table introduces a dependency on the `Lean.Name`
implementation. So, all standalone applications will depend on it.
3- We are not storing arity 0 constants in the table.
This one should be easy to fix in the future.
We are going to start making drastic changes in the parser,
elaborator, attributes, etc. Examples:
- No View objects. I am going to implement match_syntax.
- No RecT in the parser. I am going to implement parser extensions
using an approach similar to the one I used to implement environment
extensions.
- No Parsec. I will use an approach similar to the one used in the
experiment https://github.com/leanprover/lean4/tree/master/tests/playground/parser
It is easier to perform these changes with the new frontend disabled.
I will slowly re-active it as I apply the changes.
cc @kha
Remark: the attribute actions used by the frontend are all in IO.
These actions access attributes by name, and need access to the IO.ref
that contains all registered attributes in the system.
