Polymorphic +

gistfile1.txt

#lang racket
(require math
         (prefix-in racket: racket))

(define (+ . xs)
  (cond 
    [(andmap number? xs) (apply racket:+ xs)]
    [else                (apply matrix+ xs)]))

(+ (matrix [[1 2] [3 4]])
   (matrix [[5 6] [7 8]]))

(+ 41 1)