Implementation of Euclidean Algorithim in VimL (#654)

* Add viml to book.json

* Add euclidean algorithim in viml

Author: Mukundan Senthil

book.json

@@ -208,6 +208,10 @@
         {
           "lang": "kotlin",
           "name": "Kotlin"
+        },
+        {
+          "lang": "vim",
+          "name": "VimL"
         }
       ]
     }

contents/euclidean_algorithm/code/viml/euclidean.vim

@@ -0,0 +1,33 @@
+function s:euclid_mod(a, b)
+	let l:a = abs(a:a)
+	let l:b = abs(a:b)
+
+	while l:b != 0
+		let l:c = l:b
+		let l:b = l:a % l:b
+		let l:a = l:c
+	endwhile
+
+	return l:a
+endfunction
+
+function s:euclid_sub(a, b)
+	let l:a = abs(a:a)
+	let l:b = abs(a:b)
+
+	while l:a != l:b
+		if l:a > l:b
+			let l:a -= l:b
+		else
+			let l:b -= l:a
+		endif
+	endwhile
+
+	return l:a
+endfunction
+
+let s:check_1 = s:euclid_mod(64 * 67, 64 * 71)
+let s:check_2 = s:euclid_sub(128 * 12, 128 * 77)
+
+echo 'Modulus-based euclidean algorithm result:' s:check_1
+echo 'subtraction-based euclidean algorithm result:' s:check_2

contents/euclidean_algorithm/euclidean_algorithm.md

@@ -5,6 +5,8 @@ Computer science is (almost by definition) a science about computers -- a device
 The algorithm is a simple way to find the *greatest common divisor* (GCD) of two numbers, which is useful for a number of different applications (like reducing fractions). The first method (envisioned by Euclid) uses simple subtraction:
 
 {% method %}
+{% sample lang="vim" %}
+[import:14-27, lang="vim"](code/viml/euclidean.vim)
 {% sample lang="c" %}
 [import:17-30, lang="c_cpp"](code/c/euclidean_example.c)
 {% sample lang="cs" %}
@@ -91,6 +93,8 @@ Here, we simply line the two numbers up every step and subtract the lower value
 Modern implementations, though, often use the modulus operator (%) like so
 
 {% method %}
+{% sample lang="vim" %}
+[import:1-12, lang="vim"](code/viml/euclidean.vim)
 {% sample lang="c" %}
 [import:4-16, lang="c_cpp"](code/c/euclidean_example.c)
 {% sample lang="cs" %}
@@ -187,6 +191,8 @@ Here's a video on the Euclidean algorithm:
 ## Example Code
 
 {% method %}
+{% sample lang="vim" %}
+[import, lang="vim"](code/viml/euclidean.vim)
 {% sample lang="c" %}
 [import, lang="c_cpp"](code/c/euclidean_example.c)
 {% sample lang="cs" %}