Euclidean algorithm in coconut (#721)

Author: Amaras

book.json

@@ -212,6 +212,10 @@
         {
           "lang": "vim",
           "name": "VimL"
+        },
+        {
+          "lang": "coco",
+          "name": "Coconut"
         }
       ]
     }

contents/euclidean_algorithm/code/coconut/euclidean.coco

@@ -0,0 +1,19 @@
+def euclid_sub(a is int, 0) = a
+addpattern def euclid_sub(0, b is int) = b
+
+addpattern def euclid_sub(a is int, b is int):
+    if a < b:
+        return euclid_sub(a, b - a)
+    elif b < a:
+        return euclid_sub(a - b, b)
+    return a
+
+
+def euclid_mod(a is int, 0) = a
+addpattern def euclid_mod(0, b is int) = b
+
+addpattern def euclid_mod(a is int, b is int) = euclid_mod(b, a % b)
+
+if __name__ == '__main__':
+    print('Euclidean mod:', euclid_mod(64 * 67, 64 * 81))
+    print('Euclidean sub:', euclid_sub(128 * 12, 128 * 77))

contents/euclidean_algorithm/euclidean_algorithm.md

@@ -81,6 +81,8 @@ The algorithm is a simple way to find the *greatest common divisor* (GCD) of two
 
 {% sample lang="ps1" %}
 [import:1-14, lang="powershell"](code/powershell/euclidean_algorithm.ps1)
+{% sample lang="coco" %}
+[import:1-9, lang="coconut"](code/coconut/euclidean.coco)
 
 {% endmethod %}
 
@@ -169,6 +171,8 @@ Modern implementations, though, often use the modulus operator (%) like so
 
 {% sample lang="ps1" %}
 [import:16-27, lang="powershell"](code/powershell/euclidean_algorithm.ps1)
+{% sample lang="coco" %}
+[import:12-15, lang="coconut"](code/coconut/euclidean.coco)
 
 {% endmethod %}
 
@@ -282,6 +286,8 @@ The code snippets were taken from this [Scratch project](https://scratch.mit.edu
 
 {% sample lang="ps1" %}
 [import, lang="powershell"](code/powershell/euclidean_algorithm.ps1)
+{% sample lang="coco" %}
+[import, lang="coconut"](code/coconut/euclidean.coco)
 
 {% endmethod %}