Lisp/Scheme evaluator, see: SICP, 4.1

Port to CoffeeScript

by Dmitry Soshnikov [email protected]

(C) MIT Style License

Examples (see http://dmitrysoshnikov.com/coffee-lisp-eval/):

1. Sum:

   Input:

    (+ 1 2 3)
   

   Output:

    6
   

2. Define a variable in the Global environment:

   Input:

    (define x 10)
   

   Output:

    10 ; now x can be referred as bound variable
   

3. Define a procedure:

   Input:

    (define (sum x y)
            (+ x y))
   

   Output:

    ok ; procedure object created
   

4. Eval the sequence (block) of expression:

   Input:

    (begin (define a 10)       ; define "a" variable
           (define b 30)       ; and "b" variable
           (define (square x)
                   (* x x))    ; and a function
           (+ (square a) b))   ; and get the sum of square of "a" and "b"
   

   Output:

    130
   

5. Recursion; define the factorial function an call it:

   Input:

    (begin
      (define (factorial n)               ; define the factorial function
          (if (= n 1)
            1
            (* n (factorial (- n 1)))))
      (factorial 5))                      ; and call it for value 5
   

   Output:

    120
   

6. Map the list with a lambda expression:

   Input:

    (map (lambda (x) (* x x)) ; anonymous function
          (list 1 2 3 4))      ; maps the list to '(1 4 9 16)
   

   Output:

    (1 4 9 16)