added support for environment.variables

config.nix

@@ -14,6 +14,7 @@ let
     };
 
   config =
+    { config, lib, pkgs, ... }:
     {
       environment.systemPackages =
         [ pkgs.lnl.vim
@@ -30,14 +31,16 @@ let
           pkgs.nox
         ];
 
-      environment.etc."profile".text = ''
-        export HOMEBREW_CASK_OPTS="--appdir=/Applications/cask"
+      environment.variables.HOMEBREW_CASK_OPTS = "--appdir=/Applications/cask";
 
+      environment.etc."profile".text = ''
         conf=$HOME/src/nixpkgs-config
         pkgs=$HOME/.nix-defexpr/nixpkgs
 
         alias ls='ls -G'
         alias l='ls -hl'
+
+        source ${config.system.build.setEnvironment}
       '';
 
       environment.etc."tmux.conf".text = ''
@@ -49,6 +52,8 @@ let
         set -g base-index 1
         set -g renumber-windows on
 
+        setw -g mode-keys vi
+
         bind c new-window -c '#{pane_current_path}'
         bind % split-window -v -c '#{pane_current_path}'
         bind '"' split-window -h -c '#{pane_current_path}'
@@ -102,6 +107,8 @@ in {
         set et sw=2 ts=2
         set bs=indent,start
 
+        set nowrap
+
         set list
         set listchars=tab:»·,trail:·,extends:⟩,precedes:⟨
         set fillchars+=vert:\ ,stl:\ ,stlnc:\ 

modules/environment.nix

@@ -6,6 +6,12 @@ let
 
   cfg = config.environment;
 
+  exportVariables =
+    mapAttrsToList (n: v: ''export ${n}="${v}"'') cfg.variables;
+
+  exportedEnvVars =
+    concatStringsSep "\n" exportVariables;
+
 in {
   options = {
 
@@ -31,10 +37,28 @@ in {
       description = "List of additional package outputs to be symlinked into <filename>/run/current-system/sw</filename>.";
     };
 
+    environment.variables = mkOption {
+      default = {};
+      description = ''
+        A set of environment variables used in the global environment.
+        These variables will be set on shell initialisation.
+        The value of each variable can be either a string or a list of
+        strings.  The latter is concatenated, interspersed with colon
+        characters.
+      '';
+      type = types.attrsOf (types.loeOf types.str);
+      apply = mapAttrs (n: v: if isList v then concatStringsSep ":" v else v);
+    };
+
+
   };
 
   config = {
 
+    system.build.setEnvironment = pkgs.writeText "set-environment" ''
+      ${exportedEnvVars}
+    '';
+
     system.path = pkgs.buildEnv {
       name = "system-path";
       paths = cfg.systemPackages;