add piston nix pkg for mono-basic

runtimes/default.nix

@@ -62,4 +62,5 @@ args: {
     "node-coffeescript" = import ./node-coffeescript.nix args;
     "jvm-scala" = import ./jvm-scala.nix args;
     "llvm_ir" = import ./llvm_ir.nix args;
+    "mono-basic" = import ./mono-basic.nix args;
 }

runtimes/mono-basic.nix

@@ -0,0 +1,47 @@
+{pkgs, piston, ...}:
+let
+    pkg = pkgs.mono;
+in piston.mkRuntime {
+    language = "basic";
+    version = pkg.version;
+    runtime = "mono";
+
+    aliases = [
+        "vb"
+        "mono-vb"
+        "mono-basic"
+        "visual-basic"
+    ];
+
+    compile = ''
+        rename 's/$/\.vb/' "$@" # Add .vb extension
+        ${pkg}/bin/vbc -out:out -sdkpath:${pkg}/lib/mono/4.8-api *.vb
+    '';
+
+    run = ''
+        shift
+        ${pkg}/bin/mono out.exe "$@"
+    '';
+
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.vb" = ''
+                    Imports System
+
+                    Module Module1
+
+                        Sub Main()
+                            Console.WriteLine("OK")
+                        End Sub
+
+                    End Module
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.vb";
+        })
+    ];
+}