June 2018 Update

Task/Run-length-encoding/Ceylon/run-length-encoding.ceylon

@@ -0,0 +1,31 @@
+shared void run() {
+
+    "Takes a string such as aaaabbbbbbcc and returns 4a6b2c"
+    String compress(String string) {
+        if (exists firstChar = string.first) {
+            if (exists index = string.firstIndexWhere((char) => char != firstChar)) {
+                return "``index````firstChar````compress(string[index...])``";
+            }
+            else {
+                return "``string.size````firstChar``";
+            }
+        }
+        else {
+            return "";
+        }
+    }
+
+    "Takes a string such as 4a6b2c and returns aaaabbbbbbcc"
+    String decompress(String string) =>
+            let (runs = string.split(Character.letter, false).paired)
+    		"".join {
+        		for ([length, char] in runs)
+        		if (is Integer int = Integer.parse(length))
+        		char.repeat(int)
+        	};
+
+    assert (compress("aaaabbbbbaa") == "4a5b2a");
+    assert (decompress("4a6b2c") == "aaaabbbbbbcc");
+    assert (compress("WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW") == "12W1B12W3B24W1B14W");
+    assert (decompress("24a") == "aaaaaaaaaaaaaaaaaaaaaaaa");
+}