ds: link the resultTree in the dataset

garlic/ds/py.nix

@@ -0,0 +1,34 @@
+{
+  stdenv
+, python3
+, gzip
+}:
+
+{
+  script,
+  compress ? true
+}:
+
+tree:
+
+stdenv.mkDerivation {
+  name = "dataset";
+  preferLocalBuild = true;
+  phases = [ "installPhase" ];
+  buildInputs = [ python3 gzip ];
+  installPhase = ''
+    mkdir -p $out
+    ln -s ${tree} $out/tree
+    ln -s ${script} $out/script
+
+    COMPRESS_DATASET=${toString compress}
+
+    if [ $COMPRESS_DATASET ]; then
+      python $out/script $out/tree | gzip > $out/dataset.json.gz
+      ln -s dataset.json.gz $out/dataset
+    else
+      python $out/script $out/tree > $out/dataset.json
+      ln -s dataset.json $out/dataset
+    fi
+  '';
+}