From 92ffb477ebdb0b5ce3c0e08f7eda0e602905841f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Fri, 2 Jun 2023 13:34:01 +0100
Subject: [PATCH] Add languages.python.version

---
 examples/python/.test.sh         |  4 ++++
 examples/python/devenv.nix       |  6 ++++++
 examples/python/devenv.yaml      |  5 +++++
 src/modules/languages/python.nix | 24 +++++++++++++++++++++++-
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100755 examples/python/.test.sh
 create mode 100644 examples/python/devenv.nix
 create mode 100644 examples/python/devenv.yaml

diff --git a/examples/python/.test.sh b/examples/python/.test.sh
new file mode 100755
index 000000000..08910a4a6
--- /dev/null
+++ b/examples/python/.test.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+set -ex
+[ "$(command -v python)" = "$PWD/.devenv/state/venv/bin/python" ]
+python --version | grep "3.7.16"
diff --git a/examples/python/devenv.nix b/examples/python/devenv.nix
new file mode 100644
index 000000000..ab39b4534
--- /dev/null
+++ b/examples/python/devenv.nix
@@ -0,0 +1,6 @@
+{ pkgs, ... }:
+
+{
+  languages.python.enable = true;
+  languages.python.version = "3.7.16";
+}
diff --git a/examples/python/devenv.yaml b/examples/python/devenv.yaml
new file mode 100644
index 000000000..21272489a
--- /dev/null
+++ b/examples/python/devenv.yaml
@@ -0,0 +1,5 @@
+inputs:
+  nixpkgs:
+    url: github:NixOS/nixpkgs/nixpkgs-unstable
+  nixpkgs-python:
+    url: github:cachix/nixpkgs-python
\ No newline at end of file
diff --git a/src/modules/languages/python.nix b/src/modules/languages/python.nix
index 807fecf0f..ab1c2e561 100644
--- a/src/modules/languages/python.nix
+++ b/src/modules/languages/python.nix
@@ -1,8 +1,16 @@
-{ pkgs, config, lib, ... }:
+{ pkgs, config, lib, inputs, ... }:
 
 let
   cfg = config.languages.python;
 
+  nixpkgs-python = inputs.nixpkgs-python or (throw ''
+    To use languages.python.version, you need to add the following to your devenv.yaml:
+
+      inputs:
+        nixpkgs-python:
+          url: github:cachix/nixpkgs-python
+  '');
+
   venvPath = "${config.env.DEVENV_STATE}/venv";
 
   initVenvScript = pkgs.writeShellScript "init-venv.sh" ''
@@ -96,6 +104,16 @@ in
       description = "The Python package to use.";
     };
 
+    version = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = ''
+        The Python version to use.
+        This automatically sets the `languages.python.package` using [nixpkgs-python](https://github.com/cachix/nixpkgs-python).
+      '';
+      example = "3.11 or 3.11.2";
+    };
+
     venv.enable = lib.mkEnableOption "Python virtual environment";
 
     poetry = {
@@ -138,6 +156,10 @@ in
 
     languages.python.poetry.activate.enable = lib.mkIf cfg.poetry.enable (lib.mkDefault true);
 
+    languages.python.package = lib.mkMerge [
+      (lib.mkIf (cfg.version != null) (nixpkgs-python.packages.${pkgs.stdenv.system}.${cfg.version} or throw "Unsupported Python version, see https://github.com/cachix/nixpkgs-python#supported-python-versions"))
+    ];
+
     packages = [
       cfg.package
     ] ++ (lib.optional cfg.poetry.enable cfg.poetry.package);