[#24] New language: Dafny

backend/src/langs.ts

@@ -849,6 +849,17 @@ void main()
 {
     writeln("Hello, world!");
 }
+`,
+  },
+  dafny: {
+    aliases: ["dfy"],
+    name: "Dafny",
+    main: "main.dfy",
+    compile: "dafny main.dfy",
+    run: "mono main.exe",
+    template: `method Main() {
+  print "Hello, world!\\n";
+}
 `,
   },
   dart: {

scripts/docker-install-phase3a.bash

@@ -106,6 +106,10 @@ crystal
 # Curry
 pakcs
 
+# Dafny
+dafny
+mono-runtime
+
 # Dart
 dart