Association Lists

Make the following functions

• Get: Given a property name and an alist, return the associated value.
  (get 'age '((height 19) (age 3) (weight 12))) returns '3.
  (get 'grade '((height 19) (age 3) (weight 12))) returns '().

• Set: Given a property name, a property value, and an alist, returns a new alist with the property-value tuple in the returned list exactly once. Order of elements in the alist does not matter.
  (set 'age 12 '((height 19) (age 3) (weight 12))) returns '((height 19) (age 12) (weight 12))

• Delete: Given a property name, and an alist, returns a new alist with the property-value removed. Order of elements in the alist does not matter.
  (delete 'age '((height 19) (age 3) (weight 12))) returns '((height 19) (weight 12))

I'm fully aware that the web is filled with sample code to do these things. Use of such code is cheating! I shall check.

(define (test)
  (display (set 'a 1 '((a 10) (b 11) (c 12))))
  (newline)
  (display (set 'd 4 '((a 10) (b 11) (c 12))))
  (newline)
  (display (eqv? 10 (get 'age (set 'age 10 '(())))))
  (display (eqv? '() (get 'age '(()))))
  (display (eqv? 10 (get 'age (set 'age 10 '((age 8) (height 6) (weight 3))))))
  (display (eqv? 10 (get 'height (set 'height 10 '((age 8) (height 6) (weight 3))))))
  (display (eqv? 10 (get 'age (set 'age 10 '((width 4) (age 8) (height 6) (weight 3))))))
  (display (eqv? 7 (get 'weight (set 'weight 7 '((age 8) (height 6) (weight 3))))))
  (display (eqv? 'fifth (get 'grade (set 'grade 'fifth '((age 8) (height 6) (weight 3))))))
  (display (eqv? '() (get 'missing (set 'age 10 '((age 8) (height 6) (weight 3))))))
  (display (eqv? 10 (get 'age (set 'age 10 '()))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((spam 10))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((nospam 10))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '()))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((fred 5) (steve 7) (spam 10))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((spam 10) (wilma 4) (fred 2) (fry yes))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((wilma 10) (spam yes) (fred 2) (fry yes))))

  (display '(“Deleting spam from list”))
  (display (delete 'spam '((nospam 10) (wilma 4) (fred 2) (fry yes))))

)