Make predicate declarations hashable

src/ast.rs

@@ -1,4 +1,4 @@
-#[derive(PartialEq)]
+#[derive(Eq, Hash, PartialEq)]
 pub struct PredicateDeclaration
 {
 	pub name: String,

src/format.rs

@@ -72,13 +72,7 @@ impl std::fmt::Display for crate::VariableDeclaration
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
 	{
-		match &self.domain
+		write!(format, "{:?}", &self)
-		{
-			crate::Domain::Program => write!(format, "X")?,
-			crate::Domain::Integer => write!(format, "N")?,
-		};
-
-		write!(format, "{}", &self.name)
 	}
 }
 

src/parse.rs

@@ -483,9 +483,9 @@ fn formula_precedence_0(i: &str) -> IResult<&str, crate::Formula>
 {
 	alt
 	((
+		comparison,
 		predicate,
 		boolean,
-		comparison,
 		formula_parenthesized
 	))(i)
 }
@@ -845,6 +845,13 @@ mod tests
 					Box::new(crate::Term::Integer(9)),
 				),
 			))));
+
+		assert_eq!(crate::formula("n = 5"), Ok(("",
+			crate::Formula::Equal
+			(
+				crate::Term::Symbolic("n".to_string()),
+				crate::Term::Integer(5),
+			))));
 	}
 
 	#[test]