feat(haskell): ghc-with-packages

modules/home/haskell.nix

@@ -0,0 +1,31 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.sydnix.haskell;
+in {
+  options.sydnix.haskell.enable =
+    lib.mkEnableOption "Haskell";
+
+  config = lib.mkIf cfg.enable {
+    # Convenient shorthand for quickly opening Haskell REPLs.
+    programs.bash.profileExtra =
+      builtins.readFile ./haskell/ghc-with-packages.sh;
+
+    home.file.".ghc/ghci.conf".text = ''
+      :set prompt "\x1b[38;5;5mλ>\x1b[0m "
+      :set prompt-cont "\x1b[38;5;5m|>\x1b[0m "
+    '';
+
+    sydnix.impermanence.cache.directories =
+      let xdg-cache-dir =
+            config.home.cacheHome
+              or "${config.home.homeDirectory}/.cache";
+      in [
+        # We don't want to rebuild Hackage simply due to a reboot, do we?  }:)
+        (lib.removePrefix "${config.home.homeDirectory}/"
+          "${xdg-cache-dir}/cabal")
+        ".stack"
+      ];
+  };
+}
+