Fix syntax bugs

content/docs/guide/operators.mdx

@@ -86,13 +86,13 @@ Macro calls use `!` followed by parentheses, brackets, or braces.
 let add = (a, b) => a + b;
 let result = add(2, 3);  // 5
 
-let square = f64 x => x * x;
+f64 fn() square = (x) => x * x;
 ```
 
 Closures can have explicit return types:
 
 ```mist
-let transform = i32 x => {
+let transform = i32 (x) => {
     x * 2
 };
 ```