From c9495ea8812b8f3c23e7ae13492a8199bb42a1d9 Mon Sep 17 00:00:00 2001
From: Timothy DeHerrera <tim.deh@pm.me>
Date: Mon, 13 Jul 2020 20:00:47 -0600
Subject: [PATCH] direnv: use `nix print-dev-env`

In order to increase determinism in the build environment, we are
having direnv load the shell environment from the flake's `devShell`
output, instead of the traditional `nix-shell` approach. Of course,
one can still enter a `nix-shell` manually on a system without flake
support installed.
---
 .envrc    | 6 +++++-
 flake.nix | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/.envrc b/.envrc
index 1d953f4..261d630 100644
--- a/.envrc
+++ b/.envrc
@@ -1 +1,5 @@
-use nix
+# reload when these files change
+watch_file flake.nix
+watch_file flake.lock
+# load the flake devShell
+eval "$(nix print-dev-env)"
diff --git a/flake.nix b/flake.nix
index 7c4fde4..f6a54e9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -40,6 +40,8 @@
           import ./hosts (inputs // { inherit system pkgs unstablePkgs; });
       in configs;
 
+      devShell."${system}" = import ./shell.nix { inherit pkgs; };
+
       overlay = import ./pkgs;
 
       overlays = let