* refactor: a bit
* fix: named completion
* dev: replace complete_literal by complete_type
* dev: remove unused code
* dev: basic interner
* dev: basic types
* dev: type operations
* dev: migrate all type definitions
* dev: check syntax and builtin types
* dev: make TypeSimplifier simply work
* dev: make TypeDescriber simply work
* dev: make TypeChecker simply work
* dev: recover type check
* fix: context check
* fix: use after free in seen fields
* fix: typed with
* fix: record type on field
* dev: check type of constructors and element containing
* dev: show sig by type
* fix: mixed context checking
* QAQ
* >_<
* dev: fix documents
