From 664086fa4c9eb05bbd986cc4d6f41325efa1491b Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Thu, 19 Oct 2023 01:02:01 +0100
Subject: [PATCH] lib/shell: add appendToVar function

---
 modules/home-environment.nix | 5 +++--
 modules/lib/shell.nix        | 8 ++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index 69d04a124..3533ea2c4 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -579,8 +579,9 @@ in
         ${config.lib.shell.exportAll cfg.sessionVariables}
       '' + concatStringsSep "\n"
         (mapAttrsToList
-          (env: values: ''
-            export ${env}="''$${env}''${${env}:+:}${concatStringsSep ":" values}"'')
+          (env: values: config.lib.shell.export
+            env
+            (config.lib.shell.appendToVar ":" env values))
           cfg.sessionSearchVariables)
         + cfg.sessionVariablesExtra;
     };
diff --git a/modules/lib/shell.nix b/modules/lib/shell.nix
index 5e5743f51..cdcfdefa5 100644
--- a/modules/lib/shell.nix
+++ b/modules/lib/shell.nix
@@ -1,6 +1,14 @@
 { lib }:
 
 rec {
+  # Produces a Bourne shell like statement that appends new values to
+  # an possibly existing variable, using sep(ator).
+  # Example:
+  #   appendToVar ":" "PATH" [ "$HOME/bin" "$HOME/.local/bin" ]
+  #   => "$PATH\${PATH:+:}$HOME/bin:$HOME/.local/bin"
+  appendToVar = sep: n: v:
+    "\$${n}\${${n}:+${sep}}${lib.concatStringsSep sep v}";
+
   # Produces a Bourne shell like variable export statement.
   export = n: v: ''export ${n}="${toString v}"'';