- Unified math operations into a single self-referential enum
- Walk now visits the children of a node, rather than the node itself
- The old behavior was super confusing, and led to numerous stack overflows.
- Renamed literal Types to reflect their literal nature
- This allows for consistent naming across future non-literal Types
- Complicated lexer Rules have been split into composable sub-rules,
and moved into the Rule struct.
- This improves modularity, and allows sharing of sub-rules across rules.
- Documented each lexer rule with (at least) a one-line blurb
describing its function
