Problem Statement

Multiply two matrices together. They can be of any dimensions, so long as the number of columns of the first matrix is equal to the number of rows of the second matrix.

Let's start with the solution:

(define (matrix-multiply matrix1 matrix2)
  (map
   (lambda (row)
    (apply map
     (lambda column
      (apply + (map * row column)))
     matrix2))
   matrix1))