Question

Imagine an arithmetic expression such as (+ 1 (* 2 (- 3 5))) being thought of as a tree-like structure with numbers at the leaves and operator symbols at the interior nodes like below:

     +
   /   \
  1     *
       /  \
      2    -
          /  \
         3    5

each node can be expressed by a three element list: (left-operand operator right-operand)

I am trying to write a function
(make-expr left-op operator right-op)

that produces
(left-op operator right-op)

for example:
(make-expr '(6 * 3) '+ '(5 -2)) => ((6 * 3) + (5 - 2))

Answer 1

> (list '(6 * 3) '+ '(5 - 2))
((6 * 3) + (5 - 2)

Yes, it’s as simple as using the list function.