Concrete Expressions

(make-binop '+ 5 10)
        ; ==> (5 + 10)
(make-binop '* (make-binop '+ 3 7) 5))
        ; ==> ((3 + 7) * 5)
(make-binop '+ 'x 10))
        ; ==> (x + 10)
(make-binop '* (make-binop '+ 'x 7) 'y))
        ; ==> ((x + 7) * y)

Jim Miller