Add a validation step back.

src/syntax/simplify.rs

@@ -1,4 +1,4 @@
-use crate::syntax::ast::{Program, Statement, Expression};
+use crate::syntax::ast::{Expression, Program, Statement};
 
 impl Program {
     pub fn simplify(mut self) -> Self {
@@ -40,10 +40,14 @@ impl Expression {
 
                 let new_name = format!("<{}:{}>", base_name, *gensym_index);
                 *gensym_index += 1;
-                prereqs.push(Statement::Binding(loc.clone(), new_name.clone(), Expression::Primitive(loc.clone(), prim, new_exprs)));
+                prereqs.push(Statement::Binding(
+                    loc.clone(),
+                    new_name.clone(),
+                    Expression::Primitive(loc.clone(), prim, new_exprs),
+                ));
 
                 (prereqs, Expression::Reference(loc, new_name))
             }
         }
     }
-}
+}