be more specific with strings

src/ast.rs

@@ -1,3 +1,5 @@
+pub type Ident = String;
+
 #[derive(Debug, Clone)]
 pub enum Statement {
 	Assign {
@@ -5,7 +7,7 @@ pub enum Statement {
 		source: Box<Expression>,
 	},
 	Call {
-		callee: String,
+		callee: Ident,
 		args: Vec<Expression>,
 	},
 }
@@ -13,7 +15,7 @@ pub enum Statement {
 #[derive(Debug, Clone)]
 pub enum Location {
 	Variable {
-		name: String,
+		name: Ident,
 	},
 	Field {
 		table: Box<Location>,
@@ -26,7 +28,7 @@ pub enum Expression {
 	Constant(Constant),
 	Variable(Location),
 	Call {
-		callee: String,
+		callee: Ident,
 		args: Vec<Expression>,
 	},
 }