Syntax
DEFINED? name
Explanation
DEFINED? outputs TRUE if the input is a name of a primitive procedure or a user-defined procedure; otherwise; it outputs FALSE.
Examples
? DEFINED? "FORWARD
Result: TRUE
? DEFINED? "BLIMP
Result: FALSE
? TO MYPROC
> PRINT [THIS IS MY PROCEDURE.]
> END
MYPROC defined
? IF DEFINED? "MYPROC THEN MYPROC
THIS IS MY PROCEDURE.
?