add piston nix pkg for groovy

runtimes/default.nix

@@ -43,4 +43,5 @@ args: {
     "openjdk-java" = import ./openjdk-java.nix args;
     "iverilog" = import ./iverilog.nix args;
     "ghc-haskell" = import ./ghc-haskell.nix args;
+    "groovy" = import ./groovy.nix args;
 }

runtimes/groovy.nix

@@ -0,0 +1,55 @@
+{pkgs, piston, ...}:
+let
+    pkg = pkgs.groovy;
+    jre = pkgs.jre;
+    awk = pkgs.gawk;
+    sed = pkgs.gnused;
+    grep = pkgs.gnugrep;
+in piston.mkRuntime {
+    language = "groovy";
+    version = pkg.version;
+
+    aliases = [
+        "gvy"
+    ];
+
+    compile = ''
+        # Groovyc has some dependencies on GNU grep, sed, and awk in their startup script
+        export PATH="$PATH:${awk}/bin:${sed}/bin:${grep}/bin"
+
+        # Compile groovy scripts into a separate "classes" directory
+        # NOTE: - Main file MUST be a groovy script 
+        #       - not supporting object class entry points as of now
+        ${pkg}/bin/groovyc -d classes "$@"
+
+        # Create the Manifest and include groovy jars:
+        # NOTE: - main class will be the first file ('.' becomes '_' and without the extension)
+        #       - groovy lib jars MUST be in the class path in order to work properly
+        echo "Main-Class: $(sed 's/\./\_/g'<<<''${1%.*})
+        Class-Path:  $(echo ${pkg}/lib/*.jar | sed 's/\s/\n  /g')
+
+        " > manifest.txt
+
+        # Create the jar from the manifest and classes
+        ${jre}/bin/jar cfm out.jar manifest.txt -C classes .
+    '';
+
+    run = ''
+        shift
+        ${jre}/bin/java -jar out.jar "$@"
+    '';
+
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.groovy" = ''
+                    println 'OK'
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.groovy";
+        })
+    ];
+}