Nix development environment using direnv and a flake.nix (pyproject.nix and uv2nix)

Author: arunoruto

.envrc

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+# use flake .
+use flake .#uv2nix

flake.lock

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+# Sources:
+# https://pyproject-nix.github.io/pyproject.nix/use-cases/pyproject.html
+# https://pyproject-nix.github.io/uv2nix/usage/hello-world.html
+
+{
+  description = "PyFracVAL flake devenv";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+    pyproject-nix = {
+      url = "github:pyproject-nix/pyproject.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    uv2nix = {
+      url = "github:pyproject-nix/uv2nix";
+      inputs = {
+        pyproject-nix.follows = "pyproject-nix";
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+
+    pyproject-build-systems = {
+      url = "github:pyproject-nix/build-system-pkgs";
+      inputs = {
+        pyproject-nix.follows = "pyproject-nix";
+        uv2nix.follows = "uv2nix";
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+
+    flake-parts = {
+      url = "github:hercules-ci/flake-parts";
+    };
+  };
+
+  outputs =
+    inputs@{
+      flake-parts,
+      nixpkgs,
+      uv2nix,
+      pyproject-nix,
+      pyproject-build-systems,
+      ...
+    }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
+        "x86_64-linux"
+      ];
+      perSystem =
+        {
+          self',
+          pkgs,
+          lib,
+          ...
+        }:
+        let
+          project = pyproject-nix.lib.project.loadPyproject { projectRoot = ./.; };
+          workspace = uv2nix.lib.workspace.loadWorkspace { workspaceRoot = ./.; };
+
+          overlay = workspace.mkPyprojectOverlay {
+            sourcePreference = "wheel";
+          };
+
+          pyprojectOverrides = final: prev: {
+            numba = prev.numba.overrideAttrs (old: {
+              buildInputs = (old.buildInputs or [ ]) ++ [ pkgs.tbb_2021_11 ];
+            });
+          };
+
+          python = pkgs.python3;
+
+          pythonSet =
+            (pkgs.callPackage pyproject-nix.build.packages {
+              inherit python;
+            }).overrideScope
+              (
+                lib.composeManyExtensions [
+                  pyproject-build-systems.overlays.default
+                  overlay
+                  pyprojectOverrides
+                ]
+              );
+
+        in
+        {
+          packages = {
+            default = self'.packages.pyfracval;
+            pyfracval = python.pkgs.buildPythonPackage (
+              (project.renderers.buildPythonPackage { inherit python; }) // { env.CUSTOM_ENVVAR = "hello"; }
+            );
+            pyfracval-env = pythonSet.mkVirtualEnv "pyfracval-env" workspace.deps.default;
+          };
+
+          devShells = {
+            default =
+              let
+                arg = project.renderers.withPackages {
+                  inherit python;
+                  extras = [
+                    # "test"
+                  ];
+                };
+
+                pythonEnv = python.withPackages arg;
+              in
+              pkgs.mkShell {
+                packages = [
+                  pythonEnv
+                  self'.packages.pyfracval
+                ];
+              };
+
+            impure = pkgs.mkShell {
+              packages = [
+                python
+                pkgs.uv
+              ];
+              shellHook = ''
+                unset PYTHONPATH
+              '';
+            };
+
+            uv2nix =
+              let
+                editableOverlay = workspace.mkEditablePyprojectOverlay {
+                  root = "$REPO_ROOT";
+                };
+
+                editablePythonSet = pythonSet.overrideScope editableOverlay;
+
+                virtualenv = editablePythonSet.mkVirtualEnv "pyfracval-dev-env" (
+                  workspace.deps.default
+                  // {
+                    pyfracval = [
+                      # "explore"
+                      # "test"
+                    ];
+                  }
+                );
+
+              in
+              pkgs.mkShell {
+                packages = [
+                  virtualenv
+                  pkgs.uv
+                ];
+                shellHook = ''
+                  unset PYTHONPATH
+                  export REPO_ROOT=$(git rev-parse --show-toplevel)
+                '';
+              };
+          };
+        };
+    };
+}