Learn Scheme - 10 Code Examples & CST Typing Practice Test

Scheme is a minimalist, functional programming language in the Lisp family, emphasizing recursion, first-class functions, and symbolic computation. It is widely used in education, research, and AI for its simplicity and powerful abstraction capabilities.

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Scheme Counter and Theme Toggle Scheme Simple Addition Scheme Factorial Scheme Fibonacci Sequence Scheme Max of Two Numbers Scheme List Sum Scheme Even Numbers Filter Scheme Conditional Counter Increment Scheme Resettable Counter Scheme Theme Toggle Only

Learn SCHEME with Real Code Examples

Updated Nov 20, 2025

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Code Sample Descriptions

Scheme Counter and Theme Toggle

(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.

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Scheme Simple Addition

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

Adds two numbers and prints the result.

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Scheme Factorial

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

Calculates factorial recursively.

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Scheme Fibonacci Sequence

(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.

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Scheme Max of Two Numbers

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

Finds the maximum of two numbers.

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Scheme List Sum

(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.

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Scheme Even Numbers Filter

(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.

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Scheme Conditional Counter Increment

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

Increment counter only if less than 5.

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Scheme Resettable Counter

(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.

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Scheme Theme Toggle Only

(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.

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Frequently Asked Questions about Scheme

What is Scheme?

What are the primary use cases for Scheme?

Functional programming education. Symbolic computation and AI. DSL (domain-specific language) design. Prototyping algorithms. Scripting within research software. Teaching recursion and higher-order functions

What are the strengths of Scheme?

Extremely flexible and expressive. Great for learning functional programming. Encourages elegant recursion and abstraction. Lightweight and portable. Macros enable DSL creation

What are the limitations of Scheme?

Not widely used in industry. Minimal standard libraries. Performance may lag behind compiled languages. GUI and system libraries are limited. Requires understanding of recursion and functional concepts

How can I practice Scheme typing speed?

CodeSpeedTest offers 10+ real Scheme code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Code Sample Descriptions

Scheme Counter and Theme Toggle

(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.

Let’s Try →

Scheme Simple Addition

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

Adds two numbers and prints the result.

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Scheme Factorial

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

Calculates factorial recursively.

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Scheme Fibonacci Sequence

(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.

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Scheme Max of Two Numbers

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

Finds the maximum of two numbers.

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Scheme List Sum

(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.

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Scheme Even Numbers Filter

(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.

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Scheme Conditional Counter Increment

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

Increment counter only if less than 5.

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Scheme Resettable Counter

(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.

Let’s Try →

Scheme Theme Toggle Only

(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.

Let’s Try →

Frequently Asked Questions about Scheme

What is Scheme?

What are the primary use cases for Scheme?

What are the strengths of Scheme?

Extremely flexible and expressive. Great for learning functional programming. Encourages elegant recursion and abstraction. Lightweight and portable. Macros enable DSL creation

What are the limitations of Scheme?

How can I practice Scheme typing speed?

CodeSpeedTest offers 10+ real Scheme code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.