DEFINED?
Syntax DEFINED? name
 
Explanation DEFINED? reports TRUE if the input is a name of a primitive procedure or a user-defined procedure; otherwise it reports FALSE.

Compare with PROCEDURE?, which reports TRUE only if the input is a user-defined procedure, and PRIMITIVE?, which reports TRUE only if the input is a built-in command.
 

Examples DEFINED? "FORWARD 
Result: TRUE 
DEFINED? "BLIMP 
Result: FALSE 
TO MYPROC 
     PRINT [THIS IS MY PROCEDURE.]
END
MYPROC defined
MYPROC
THIS IS MY PROCEDURE. 
DEFINED? "MYPROC
Result: TRUE

TopIndex