Add Alloy language (#541)

Alloy is an open source language and analyzer for software modeling.

Homepage: http://alloytools.org/

README.md

@@ -285,6 +285,7 @@ ActionScript
 Ada
 Agda
 Alex
+Alloy
 Asn1
 Asp
 AspNet

languages.json

@@ -24,6 +24,11 @@
       "multi_line_comments": [["{-", "-}"]],
       "extensions": ["agda"]
     },
+    "Alloy": {
+      "line_comment": ["--", "//"],
+      "multi_line_comments": [["/*", "*/"]],
+      "extensions": ["als"]
+    },
     "Arduino": {
       "name": "Arduino C++",
       "line_comment": ["//"],

tests/alloy.als

@@ -0,0 +1,18 @@
+// 18 lines 10 code 3 comments 5 blanks
+
+sig Node {
+    edge: set Node
+}
+
+------------------------------------------------------------------------
+
+pred self_loop[n: Node] {
+  n in n.edge
+}
+
+pred all_self_loop {
+  all n: Node | self_loop[n]
+}
+
+/* Comments started by /* don't nest */
+run all_self_loop