<-varname ->!

Pops a value from the stack and treats it as a variable name, then pops another value from the stack and assigns it to that variable.

# Store a number in the variable named xyz 
123 ->xyz 
# Build a string by concatenating "xy" and "z". 
# The result is "xyz". Use that as the name of a var and read its contents. 
# The result of the read is pushed to the stack and traced. 
"xy" "z" concat 
<-! trace