Add elm-format example

devshell.nix

@@ -19,6 +19,7 @@ devshell.mkShell {
     clang
 
     # Code formatters
+    elmPackages.elm-format
     haskellPackages.ormolu
     haskellPackages.cabal-install
     haskellPackages.ghc

examples/monorepo/elm/elm.json

@@ -0,0 +1,24 @@
+{
+    "type": "application",
+    "source-directories": [
+        "src"
+    ],
+    "elm-version": "0.19.1",
+    "dependencies": {
+        "direct": {
+            "elm/browser": "1.0.2",
+            "elm/core": "1.0.5",
+            "elm/html": "1.0.0"
+        },
+        "indirect": {
+            "elm/json": "1.1.3",
+            "elm/time": "1.0.0",
+            "elm/url": "1.0.0",
+            "elm/virtual-dom": "1.0.2"
+        }
+    },
+    "test-dependencies": {
+        "direct": {},
+        "indirect": {}
+    }
+}

examples/monorepo/elm/src/Main.elm

@@ -0,0 +1,31 @@
+module Main exposing (Msg(..), main, update, view)
+
+import Browser
+import Html exposing (Html, button, div, text)
+import Html.Events exposing (onClick)
+
+
+main =
+    Browser.sandbox { init = 0, update = update, view = view }
+
+
+type Msg
+    = Increment
+    | Decrement
+
+
+update msg model =
+    case msg of
+        Increment ->
+            model + 1
+
+        Decrement ->
+            model - 1
+
+
+view model =
+    div []
+        [ button [ onClick Decrement ] [ text "-" ]
+        , div [] [ text (String.fromInt model) ]
+        , button [ onClick Increment ] [ text "+" ]
+        ]

examples/monorepo/prjfmt.toml

@@ -17,3 +17,8 @@ includes = [ "rust/" ]
 excludes = []
 command = "cargo"
 options = [ "fmt", "--" ]
+
+[formatters.elm-format]
+files = [ "*.elm" ]
+command = "elm-format"
+options = [ "--yes" ]