feat(interpreter): add method to stringify values

src/interpreter/interpreter.py

@@ -169,7 +169,7 @@ class Interpreter(Expr.Visitor[Any], Stmt.Visitor[None]):
 
     def visit_print_stmt(self, stmt: PrintStmt) -> None:
         value: Any = self.evaluate(stmt.expression)
-        print(value)
+        print(self.stringify(value))
 
     def visit_return_stmt(self, stmt: ReturnStmt) -> None:
         value: Any = None
@@ -280,3 +280,17 @@ class Interpreter(Expr.Visitor[Any], Stmt.Visitor[None]):
         if isinstance(value, (int, float)):
             return
         raise PebbleRuntimeError(clause, "For loop clauses must be numbers.")
+
+    @staticmethod
+    def stringify(obj: Any) -> str:
+        if obj is None:
+            return "null"
+        if obj is True:
+            return "true"
+        if obj is False:
+            return "false"
+        if isinstance(obj, (int, float)):
+            if obj.is_integer():
+                obj = int(obj)
+            return str(obj)
+        return obj