Split eval.rs out of ast.rs, and rename ast.rs to basic.rs. Copy it over to opt.rs, and hook up a From<> impl and a congruent(x)->bool function, and add to main.rs and test.rs. Now we actually have to make opt.rs optimize...

kv/src/grammar.lalrpop

@@ -1,6 +1,7 @@
 use std::str::FromStr;
 use std::rc::Rc;
-use crate::ast::{Form,FormT};
+use crate::basic::Form;
+use crate::eval::FormT;
 
 grammar;