Learn SCHEME with Real Code Examples

(define count 0)
(define isDark #f)

(define (updateUI)
  (display "Counter: ") (display count) (newline)
  (display "Theme: ") (display (if isDark "Dark" "Light")) (newline))

(define (increment)
  (set! count (+ count 1))
  (updateUI))

(define (decrement)
  (set! count (- count 1))
  (updateUI))

(define (reset)
  (set! count 0)
  (updateUI))

(define (toggleTheme)
  (set! isDark (not isDark))
  (updateUI))

; Simulate actions
(updateUI)
(increment)
(increment)
(toggleTheme)
(decrement)
(reset)

Demonstrates a simple counter with theme toggling using Scheme variables and console output.

(define (add a b) (+ a b))
(display (add 10 20)) (newline)

Adds two numbers and prints the result.

(define (factorial n)
  (if (<= n 1)
      1
      (* n (factorial (- n 1)))))
(display (factorial 5)) (newline)

Calculates factorial recursively.

(define (fib n)
  (if (< n 2) n
      (+ (fib (- n 1)) (fib (- n 2)))))
(for-each (lambda (i) (display (fib i)) (newline)) (iota 10))

Generates first 10 Fibonacci numbers.

(define (max a b) (if (> a b) a b))
(display (max 10 20)) (newline)

Finds the maximum of two numbers.

(define (sum-list lst)
  (if (null? lst) 0
      (+ (car lst) (sum-list (cdr lst)))))
(display (sum-list '(1 2 3 4 5))) (newline)

Sums elements of a list recursively.

(define (print-even lst)
  (for-each (lambda (x) (if (even? x) (display x) (void)) (newline)) lst))
(print-even '(1 2 3 4 5))

Prints even numbers from a list.

(define count 3)
(if (< count 5) (set! count (+ count 1)))
(display count) (newline)

Increment counter only if less than 5.

(define count 0)
(set! count (+ count 1))
(set! count (+ count 1))
(display count) (newline)
(set! count 0)
(display count) (newline)

Counter that increments and can be reset.

(define isDark #f)
(display (if isDark "Dark" "Light")) (newline)
(set! isDark (not isDark))
(display (if isDark "Dark" "Light")) (newline)
(set! isDark (not isDark))
(display (if isDark "Dark" "Light")) (newline)

Toggles theme multiple times.