I am still a lisp newbie, so I don’t know if this is cool or just wierd. Its something I made up a while back when I was first learning about cons associations:
Cons Table (this one is much better than below)
| 1 | 0 | 15 | 14 | ||||||||||
| cdaaar | caaaar | cddddr | cadddr | ||||||||||
| caaar | cdddr | ||||||||||||
| 2 | cadaar | | | | | cdaddr | 13 | ||||||||
| cdaar | — | caar | cddr | — | caddr | ||||||||
| 3 | cddaar | | | | | caaddr | 12 | ||||||||
| car | — | (cons) | — | cdr | |||||||||
| 4 | caadar | | | | | cddadr | 11 | ||||||||
| cadar | — | cdar | cadr | — | cdadr | ||||||||
| 5 | cdadar | | | | | cadadr | 10 | ||||||||
| cddar | caadr | ||||||||||||
| caddar | cdddar | caaadr | cdaadr | ||||||||||
| 6 | 7 | 8 | 9 | ||||||||||
I made the above diagram when I was first exposed to lisp in an attempt to understand all of the car/cdr functions. The problem with this model is that car and cdr are not equivalent, with car representing the first element of a list and cdr representing everything else. Apparently I will one day see functions as lists and lists as functions, so (+ 4 5 6) could simply be seen as a list where you evaluate car, the + sign and pass it cdr, which is 4 5 and 6, the values to be added.