Refactor function signatures to use slices

src/integration_test.rs

@@ -75,7 +75,7 @@ mod tests {
             .expect("Failed to compile");
         let linked = env.link(compiled);
         let func = env.instantiate(linked);
-        let result: Result<Value, String> = Ok((func.func)(vec![]));
+        let result: Result<Value, String> = Ok((func.func)(&[]));
 
         match result {
             Ok(Value::Int(20)) => (),