```
2021.10.22 07:14:33.963099 [ 3451059 ] {} <Error> Application: DB::Exception: Syntax error (in file ./user_defined/function_a_function.sql): failed at position 39 ('->'): -> ch(2)

$ cat ./user_defined/function_a_function.sql
CREATE FUNCTION a_function AS tuple() -> ch(2)
```
{
    if (name == "view")
        throw Exception("Table function view cannot be used as an expression", ErrorCodes::UNEXPECTED_EXPRESSION);
    writeString(name, ostr);
    if (parameters)
    {
        writeChar('(', ostr);
        for (auto it = parameters->children.begin(); it != parameters->children.end(); ++it)
        {
            if (it != parameters->children.begin())
                writeCString(", ", ostr);
            (*it)->appendColumnName(ostr);
        }
        writeChar(')', ostr);
    }