Use ordered sets for declarations

This replaces the unordered sets used for function and predicate
declarations with ordered sets. This is useful when these declarations
are supposed to be processed in a stable and meaningful order.

src/ast.rs

@@ -47,7 +47,7 @@ impl FunctionDeclaration
 	}
 }
 
-pub type FunctionDeclarations = std::collections::HashSet<std::rc::Rc<FunctionDeclaration>>;
+pub type FunctionDeclarations = std::collections::BTreeSet<std::rc::Rc<FunctionDeclaration>>;
 
 #[derive(Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct PredicateDeclaration
@@ -68,7 +68,7 @@ impl PredicateDeclaration
 	}
 }
 
-pub type PredicateDeclarations = std::collections::HashSet<std::rc::Rc<PredicateDeclaration>>;
+pub type PredicateDeclarations = std::collections::BTreeSet<std::rc::Rc<PredicateDeclaration>>;
 
 #[derive(Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct VariableDeclaration

src/format.rs

@@ -211,7 +211,7 @@ impl<'formula> std::fmt::Debug for FormulaDisplay<'formula>
 
 				let mut separator = " ";
 
-				for parameter in &exists.parameters
+				for parameter in exists.parameters.iter()
 				{
 					write!(format, "{}{:?}", separator, parameter)?;
 
@@ -226,7 +226,7 @@ impl<'formula> std::fmt::Debug for FormulaDisplay<'formula>
 
 				let mut separator = " ";
 
-				for parameter in &for_all.parameters
+				for parameter in for_all.parameters.iter()
 				{
 					write!(format, "{}{:?}", separator, parameter)?;