This page is part of the web mail archives of SRFI 17 from before July 7th, 2015. The new archives for SRFI 17 contain all messages, not just those from before July 7th, 2015.
>... but I fail to see the appeal of this mechanism. As far as I can >tell, a scheme implementation which conforms to this SRFI allows me >to write > >(set! (car x) 5) > >rather than > >(set-car! x 5) It's useful for syntactic (rather than procedural) abstraction. It allows you to write macros like this: ;; inc! increments whatever is stored in the "location" that ;; is its argument. (define-syntax inc! (syntax-rules () ((inc! ?loc) (set! ?loc (+ ?loc 1))))) Without SRFI-17, you can at most pass a variable as a location: (inc! x) => (set! x (+ x 1)) but with SRFI-17 you can do better: (inc! (car x)) => (set! (car x) (+ (car x) 1)) (inc! (vector-ref v i)) => (set! (vector-ref v i) (+ (vector-ref v i) 1)) --lars