SuperCollider has nested scoping of variables. A function can refer not only to its own arguments and variables, but also to those declared in any enclosing (defining) contexts.
For example, the function defined below within makeCounter can access all of the arguments and variables declared in
makeCounter. Other code can call the returned function at some later time and it can access and update the values contained in
makeCounter at the time when the inner function was instantiated.
x and z are functions which refer to different instances of the variables curVal and stepVal
Note that even though the function which defines curVal and stepVal has completed execution, its variables are still accessible to those functions that were defined within its context. This is known as lexical closure, the capturing and availability of variables defined in outer contexts by inner contexts even when the outer contexts may have completed execution.