Simple Cipher

Challenge Overview

Implement the Vigenère cipher, a simple substitution cipher.

Visit the simple-cipher exercise on Exercism to read the full instructions and download the exercise files.

Community Solutions

View Community Solutions

The following are the top 3 community solutions by stars:

Solution 1 by @mixedveges (⭐ 0) — View on Exercism
Solution 2 by @talkingaboutcode (⭐ 1) — View on Exercism
Solution 3 by @Flawless (⭐ 0) — View on Exercism

Source: Exercism fsharp/simple-cipher

💡 View Solution

module SimpleCipher

let posMod x m = ((x % m) + m) % m

let shift op (key: char) (c: char) =
    let charIndex = int c - int 'a'
    let keyShift = int key - int 'a'
    let shiftedCharIndex = posMod (op charIndex keyShift) 26
    char (shiftedCharIndex + int 'a')