Support hashing domains

src/ast.rs

@@ -53,7 +53,7 @@ pub enum Formula
 	Predicate(Predicate),
 }
 
-#[derive(PartialEq)]
+#[derive(Eq, Hash, PartialEq)]
 pub enum Domain
 {
 	Program,

src/parse.rs

@@ -100,7 +100,7 @@ fn is_uppercase_alphanumeric(c: char) -> bool
 	c.is_alphanumeric() && c.is_uppercase()
 }
 
-fn symbolic_identifier(i: &str) -> IResult<&str, String>
+pub fn symbolic_identifier(i: &str) -> IResult<&str, String>
 {
 	let (i, symbolic_identifier) = map
 	(