Here are a few macros that extend SRFI 17 getters and setters.
(push! variable item)
Calls cons on the values of item and variable, and sets variable to the result. Returns an unspecified value.
(push! (proc arg ...) item)
Calls cons on the values of item and (proc arg ...). Then evaluates ((setter proc) arg ... result), where result is the newly allocated pair. Returns an unspecified value. It is an error if proc does not have an associated setter.
(pop! variable)
Calls car and cdr on the value of variable, and sets variable to the result of cdr. Returns the result of car. It is an error if the value of variable is not a pair.
(pop! (proc arg ...))
Calls car and cdr on the value of (proc arg ...). Then evaluates ((setter proc) arg ... cdr-result), where cdr-result is the result of cdr. Returns the result of car. It is an error if the value of variable is not a pair. It is also an error if proc does not have an associated setter.
(inc! variable [ delta ])
(dec! variable [ delta ])
Calls + on the values of variable and delta, and sets variable to the result. Returns an unspecified value. It is an error if the value of variable is not a number. The default value of delta is 1 for inc! and -1 for dec!.
(inc! (proc arg ...) [ delta ])
(dec! (proc arg ...) [ delta ])
Calls + on the values of (proc arg ...) and delta. Then evaluates ((setter proc) arg ... result), where cdr-result is the result of +. Returns an unspecified value. The default value of delta is 1 for inc! and -1 for dec!. It is an error if the value of variable is not a number. It is also an error if proc does not have an associated setter.
(update! variable proc)
Applies the value of proc to the value of variable, and sets variable to the result. Returns an unspecified value. It is an error if the value of proc is not a procedure that accepts one argument.
(update! (proc arg ...) item)
Applies proc to the values of item and (proc arg ...). Then evaluates ((setter proc) arg ... result), where result is the result. Returns an unspecified value. It is an error if the value of proc is not a procedure that accepts one argument. It is also an error if proc does not have an associated setter.