add piston nix pkg for jvm-kotlin

runtimes/default.nix

@@ -37,4 +37,5 @@ args: {
     "lua" = import ./lua.nix args;
     "lolcode" = import ./lolcode.nix args;
     "sbcl-lisp" = import ./sbcl-lisp.nix args;
+    "jvm-kotlin" = import ./jvm-kotlin.nix args;
 }

runtimes/jvm-kotlin.nix

@@ -0,0 +1,39 @@
+{pkgs, piston, ...}:
+let
+    pkg = pkgs.kotlin;
+    jre = pkgs.jre;
+in piston.mkRuntime {
+    language = "kotlin";
+    version = pkg.version;
+    runtime = "jvm";
+
+    aliases = [
+        "kt"
+    ];
+
+    compile = ''
+        rename 's/$/\.kt/' "$@" # Add .kt extension
+        ${pkg}/bin/kotlinc *.kt -include-runtime -d code.jar
+    '';
+
+    run = ''
+        shift
+        ${jre}/bin/java -jar code.jar "$@"
+    '';
+
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.kt" = ''
+                    fun main() {
+                        println("OK")
+                    }
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.kt";
+        })
+    ];
+}