remove unnecessary keywords  and factorize lexer database
snapshot changes
unify
fix a subtle bug
For code written only once -- and seldomly  needs to be maintained -- the boilerplate is acceptable
tweak
a better name
tweak
make regex a directive language
move ast2pt to main for good reasons
1. so we can use DDSL in this module
2. keep in mind: still minimal dependency for this module
instead of applying filters -- we do the translation during transformation -- more efficient, and easy to reason about
try to add __PWD__ __LINE__ __FILE__ as native in Fan
simplify pat transformation
tweak
simplify exp_desc
tweak pat_desc
tweak
tweak
lazy expansion works
tweak