feat(emacs): Haskell

users/crumb/programs/haskell.nix

@@ -0,0 +1,46 @@
+{ config, lib, pkgs, ... }:
+
+{
+  # Convenient shorthand for quickly opening Haskell REPLs.
+  programs.bash.profileExtra = ''
+    # Start a GHCi REPL with the given packages made available.
+    ghci-with-packages () {
+      nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [ $@ ])" \
+        --run ghci
+    }
+
+    # Run GHC with the given packages made available.
+    ghc-with-packages () {
+      getopt -o "p" -- "$@"
+      while true; do
+        case "$1" in
+          -p)
+            packages="$1"
+            shift 2
+            ;;
+          --)
+            shift
+            break
+            ;;
+        esac
+      done
+
+      if [ $? -ne 0 ]; then
+       echo "Invalid options provided"
+       exit 1
+      fi
+
+      eval set -- "$options"
+
+      nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [ $packages ])" \
+        --run "ghc $@"
+    }
+  '';
+
+  # Some global Cabal configuration.
+  xdg.configFile.".cabal/config".text = ''
+    -- Globally-enable Nix integration.  See
+    -- https://cabal.readthedocs.io/en/3.4/nix-integration.html
+    nix: True
+  '';
+}