In racket, I'd write something like (argmax (λ(c) (string-length (customer-name c))) customers) http://docs.racket-lang.org/reference/pairs.html?q

In racket, I'd write something like (argmax (λ(c) (string-length (customer-name c))) customers) http://docs.racket-lang.org/reference/pairs.html?q=argmax#(def._((lib._racket/list..rkt)._argmax) http://docs.racket-lang.org/reference/pairs.html?q=argmax#(d...) Haskell has argmaxBy: http://hackage.haskell.org/packages/archive/list-extras/0.3.0/doc/html/Data-List-Extras-Argmax.html http://hackage.haskell.org/packages/archive/list-extras/0.3.... If your language doesn't have argmax, fold the list with the best value, like this in lisp: (define (my-argmax fun lst) (foldl (λ(prev-max elt) (if (< (fun prev-max) (fun elt)) elt prev-max)) (car lst) (cdr lst))) No extra space usage, no temporary values, no sorting; all in O(N) time. :)