Add ability to check formatting

flake.nix

@@ -38,6 +38,7 @@
             pkgs.haskellPackages.ormolu
             pkgs.haskellPackages.hlint
             pkgs.nixpkgs-fmt
+            pkgs.bash
           ];
           withHoogle = false;
         };

format.sh

@@ -1,7 +1,19 @@
-#!/usr/bin/env sh
+#!/usr/bin/env bash
+
+if [[ "$1" == "check" ]]; then
+    ormolu_flags="--mode check"
+    nixpkgs_fmt_flags="--check"
+elif [[ "$1" == "format" ]]; then
+    ormolu_flags="--mode inplace"
+    nixpkgs_fmt_flags=""
+else 
+    echo "Usage: $0 [check|format]"
+    exit 1
+fi
 
-set -o xtrace
 set -o errexit
+shopt -s globstar
+set -o xtrace
 
-fd -e hs -X ormolu -o -XTypeApplications --mode inplace {}
-nixpkgs-fmt default.nix shell.nix flake.nix
+ormolu $ormolu_flags {src,test}/**/*.hs
+nixpkgs-fmt  $nixpkgs_fmt_flags default.nix shell.nix flake.nix