The arity of a function is a synopsis of how many values it accepts and returns on the stack. If it finds an inconsistency, such as a function which sometimes returns three values, and sometimes four, it will issue an error message. You can tell MUF what arity you think your function has, and it will also issue an error message if it disagrees with your opinion. You can also tell it to accept some arity for the function, and not bother checking itself. This is sometimes useful in cases which MUF is not smart enough to analyse itself.
Some functions never return.
This is to be avoided where reasonably possible, but very occasionally you may have a function which genuinely needs to accept or return a variable number of arguments. Go to the first , previous , next , last section, table of contents .