first working shake rule

.gitignore

@@ -242,3 +242,5 @@ documentation.json
 /tests/axe-report.json
 /tests/deprecated-imports-report.txt
 /tests/VerifyExamples
+
+/_build

Shakefile.hs

@@ -0,0 +1,11 @@
+import Development.Shake
+import Development.Shake.Command
+import Development.Shake.FilePath
+import Development.Shake.Util
+
+main :: IO ()
+main = shakeArgs shakeOptions {shakeFiles = "_build"} $ do
+  "tests/elm-verify-examples.json" %> \out -> do
+    need ["elm.json"]
+    Stdout newConfig <- cmd "jq" "--indent" "4" ["{ root: \"../src\", tests: .[\"exposed-modules\"] }"] "elm.json"
+    writeFileChanged out newConfig

shell.nix

@@ -12,6 +12,8 @@ stdenv.mkDerivation {
     gnumake
     niv.niv
     jq
+    haskellPackages.ormolu
+    (haskellPackages.ghcWithPackages (ps: [ ps.shake ]))
 
     # node dependencies
     nodejs