Post Code

One recurring complaint is that nobody talks about code on /prog/. So everyone write go and write some code, any code, that does something, anything, and post it. A small explanation wouldn't go amiss either.

    ((set!!! (car x) val)
     (set-car! x val))
    ((set!!! (cdr x) val)
     (set-cdr! x val))
    ((set!!! (caar x) val)
     (set-car! (car x) val))
    ((set!!! (cadr x) val)
     (set-car! (cdr x) val))
    ((set!!! (cdar x) val)
     (set-cdr! (car x) val))
    ((set!!! (cddr x) val)
     (set-cdr! (cdr x) val))
    ((set!!! (caaar x) val)
     (set-car! (caar x) val))
    ((set!!! (caadr x) val)
     (set-car! (cadr x) val))
    ((set!!! (cadar x) val)
     (set-car! (cdar x) val))
    ((set!!! (caddr x) val)
     (set-car! (cddr x) val))
    ((set!!! (cdaar x) val)
     (set-cdr! (caar x) val))
    ((set!!! (cdadr x) val)
     (set-cdr! (cadr x) val))
    ((set!!! (cddar x) val)
     (set-cdr! (cdar x) val))
    ((set!!! (cdddr x) val)
     (set-cdr! (cddr x) val))
    ((set!!! (caaaar x) val)
     (set-car! (caaar x) val))
    ((set!!! (caaadr x) val)
     (set-car! (caadr x) val))
    ((set!!! (caadar x) val)
     (set-car! (cadar x) val))
    ((set!!! (caaddr x) val)
     (set-car! (caddr x) val))
    ((set!!! (cadaar x) val)
     (set-car! (cdaar x) val))
    ((set!!! (cadadr x) val)
     (set-car! (cdadr x) val))
    ((set!!! (caddar x) val)
     (set-car! (cddar x) val))
    ((set!!! (cadddr x) val)
     (set-car! (cdddr x) val))
    ((set!!! (cdaaar x) val)
     (set-cdr! (caaar x) val))
    ((set!!! (cdaadr x) val)
     (set-cdr! (caadr x) val))
    ((set!!! (cdadar x) val)
     (set-cdr! (cadar x) val))
    ((set!!! (cdaddr x) val)
     (set-cdr! (caddr x) val))
    ((set!!! (cddaar x) val)
     (set-cdr! (cdaar x) val))
    ((set!!! (cddadr x) val)
     (set-cdr! (cdadr x) val))
    ((set!!! (cdddar x) val)
     (set-cdr! (cddar x) val))
    ((set!!! (cddddr x) val)
     (set-cdr! (cdddr x) val))

You're using (arguably) the world's most extensible and dynamic language and you're too mentally lazy to generate those automatically? Come on.