From ace4288c9dd523a3bfb1abb4cf0c7a39a8ee90f5 Mon Sep 17 00:00:00 2001
From: Kiana Sheibani <kiana.a.sheibani@gmail.com>
Date: Tue, 7 Feb 2023 14:24:32 -0500
Subject: [PATCH] Modify flake.nix to make dev shells optional

---
 flake.nix | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/flake.nix b/flake.nix
index cf65e5a..e0f05d9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,11 +10,19 @@
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
+        inherit (pkgs) lib;
 
+        # Check if project has a shell.nix
+        hasShell = dir: (builtins.readDir ./${dir}) ? "shell.nix";
+
+        # Get all project directories
         currentDir = builtins.readDir ./.;
-        dirs = pkgs.lib.filterAttrs (_: v: v == "directory") currentDir;
-      in {
-        packages = builtins.mapAttrs (dir: _: pkgs.callPackage ./${dir} {}) dirs;
-        devShells = builtins.mapAttrs (dir: _: pkgs.callPackage ./${dir}/shell.nix {}) dirs;
-      });
+        dirs = lib.filterAttrs (_: v: v == "directory") currentDir;
+      in
+        lib.concatMapAttrs (dir: _: {
+          packages.${dir} = pkgs.callPackage ./${dir} {};
+        } // lib.optionalAttrs (hasShell dir) {
+          devShells.${dir} = pkgs.callPackage ./${dir}/shell.nix {};
+        }) dirs
+    );
 }