2 files changed, 39 insertions, 0 deletions

diff --git a/overlays/persistent-nix-shell/default.nix b/overlays/persistent-nix-shell/default.nix
new file mode 100644
index 00000000..60396335
--- /dev/null
+++ b/overlays/persistent-nix-shell/default.nix
@@ -0,0 +1,19 @@
+final: prev: {
+  persistent-nix-shell = prev.stdenv.mkDerivation {
+    name = "persistent-nix-shell";
+    src = ./persistent-nix-shell;
+
+    phases = [ "buildPhase" "installPhase" ];
+
+    inherit (final) zsh;
+
+    buildPhase = ''
+      substituteAll $src persistent-nix-shell
+    '';
+
+    installPhase = ''
+      install -m 0755 -D -t $out/bin \
+        persistent-nix-shell
+    '';
+  };
+}
diff --git a/overlays/persistent-nix-shell/persistent-nix-shell b/overlays/persistent-nix-shell/persistent-nix-shell
new file mode 100644
index 00000000..a17f6de6
--- /dev/null
+++ b/overlays/persistent-nix-shell/persistent-nix-shell
@@ -0,0 +1,20 @@
+#!@zsh@/bin/zsh
+
+set -e
+
+gcrootsDir=${PWD}/.nix-gc-roots
+
+if [[ ${#@} -ge 1 ]]; then
+  shellFile=${1}
+  shift
+else
+  shellFile=${PWD}/shell.nix
+fi
+
+set -x
+mkdir -p ${gcrootsDir}
+nix-instantiate ${shellFile} --indirect --add-root ${gcrootsDir}/shell.drv
+nix-store --indirect --add-root ${gcrootsDir}/shell.dep --realise $(nix-store --query --references ${gcrootsDir}/shell.drv)
+set +x
+
+exec nix-shell $(readlink ${gcrootsDir}/shell.drv) ${@}