Variable Exists (by reference)

Syntax

-?!

Description

Takes a string from the stack and uses it as a variable name. If the variable exists (has been assigned),1 (true) is pushed to the stack, otherwise 0 (false).

Examples

"Santa isn't r-" ->secret
 
if ("secret" -?!)
    "I know a secret" Trace
else
    "I know no secrets" Trace
endif