Adds: Refactorings of outputted Elm code and dependency updates

- Updates elixir, erlang, mix project and dependency versions.
- Updates README with updated example output code.
- Updates example input/output files.
- Fixes some credo warnings regarding application.get_env.
- Updates error messages to use properly static pointers to JSON schema
  standards.
- Migrates all types to use `typed_struct` and also adds a proper `error_type`
  union type.
- Simplifies `preamble.elm.eex` by removing all function imports and instead
  making qualified function calls, e.g. `succeed` becomes `Decode.succeed` in
  Elm decoders, and similarly for all other library calls expect the decode
  pipeline calls.
- Renames `Util.elm` to `Encode.elm` and removes function imports turning
  calls such as `encodeRequired` into `Encode.required`.
- Splits the parsing and decoding for enums into two so the `enumDecoder`
  calls a dedicated `parseEnum` function making it easier to reuse the
  `parseEnum` in other contexts.
- Updates dependencies in the generated `.tool-versions`, `package.json` and
  `elm.json` files.
- Adjusts tests accordingly to the changes above.

Author: dragonwasrobot

.gitignore

@@ -1,6 +1,8 @@
 # The packaged executable
 js2e
 /js2e_output
+node_modules
+elm-stuff
 
 # The directory Mix will write compiled artifacts to.
 /_build

.tool-versions

@@ -1,2 +1,2 @@
-erlang 22.0
-elixir 1.9.0
+erlang 24.0.6
+elixir 1.12.3

README.md

@@ -43,7 +43,7 @@ JSON schema types are described in the `lib/types` folder.
 ## Example
 
 If we supply `js2e` with the following JSON schema file, `definitions.json`:
-``` javascript
+``` json
 {
     "$schema": "http://json-schema.org/draft-07/schema#",
     "title": "Definitions",
@@ -86,39 +86,16 @@ module Data.Definitions exposing
 
 -- Schema for common types
 
-import Data.Utils
-    exposing
-        ( encodeNestedOptional
-        , encodeNestedRequired
-        , encodeOptional
-        , encodeRequired
-        )
-import Json.Decode as Decode
-    exposing
-        ( Decoder
-        , andThen
-        , at
-        , fail
-        , field
-        , index
-        , map
-        , maybe
-        , nullable
-        , oneOf
-        , succeed
-        )
+import Data.Encode as Encode
+import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Extra as Decode
 import Json.Decode.Pipeline
     exposing
         ( custom
         , optional
         , required
         )
-import Json.Encode as Encode
-    exposing
-        ( Value
-        , list
-        , object
-        )
+import Json.Encode as Encode exposing (Value)
 
 
 type Color
@@ -136,55 +113,61 @@ type alias Point =
 
 colorDecoder : Decoder Color
 colorDecoder =
-    Decode.string
-        |> andThen
-            (\color ->
-                case color of
-                    "red" ->
-                        succeed Red
+    Decode.string |> Decode.andThen (parseColor >> Decode.fromResult)
+
+
+parseColor : String -> Result String Color
+parseColor color =
+    case color of
+        "red" ->
+            Ok Red
 
-                    "yellow" ->
-                        succeed Yellow
+        "yellow" ->
+            Ok Yellow
 
-                    "green" ->
-                        succeed Green
+        "green" ->
+            Ok Green
 
-                    "blue" ->
-                        succeed Blue
+        "blue" ->
+            Ok Blue
 
-                    _ ->
-                        fail <| "Unknown color type: " ++ color
-            )
+        _ ->
+            Err <| "Unknown color type: " ++ color
 
 
 pointDecoder : Decoder Point
 pointDecoder =
-    succeed Point
+    Decode.succeed Point
         |> required "x" Decode.float
         |> required "y" Decode.float
 
 
 encodeColor : Color -> Value
 encodeColor color =
+    color |> colorToString |> Encode.string
+
+
+colorToString : Color -> String
+colorToString color =
     case color of
         Red ->
-            Encode.string "red"
+            "red"
 
         Yellow ->
-            Encode.string "yellow"
+            "yellow"
 
         Green ->
-            Encode.string "green"
+            "green"
 
         Blue ->
-            Encode.string "blue"
+            "blue"
 
 
 encodePoint : Point -> Value
 encodePoint point =
     []
-        |> encodeRequired "x" point.x Encode.float
-        |> encodeRequired "y" point.y Encode.float
+        |> Encode.required "x" point.x Encode.float
+        |> Encode.required "y" point.y Encode.float
         |> Encode.object
 ```
 
@@ -194,9 +177,9 @@ their corresponding JSON decoders and encoders.
 Furthermore, if we instead supply `js2e` with a directory of JSON schema files
 that have references across files, e.g.
 
-``` javascript
+``` json
 {
-    "$schema": "http://json-schema.org/draft-04/schema#",
+    "$schema": "http://json-schema.org/draft-07/schema#",
     "$id": "http://example.com/circle.json",
     "title": "Circle",
     "description": "Schema for a circle shape",
@@ -230,39 +213,16 @@ module Data.Circle exposing
 -- Schema for a circle shape
 
 import Data.Definitions as Definitions
-import Data.Utils
-    exposing
-        ( encodeNestedOptional
-        , encodeNestedRequired
-        , encodeOptional
-        , encodeRequired
-        )
-import Json.Decode as Decode
-    exposing
-        ( Decoder
-        , andThen
-        , at
-        , fail
-        , field
-        , index
-        , map
-        , maybe
-        , nullable
-        , oneOf
-        , succeed
-        )
+import Data.Encode as Encode
+import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Extra as Decode
 import Json.Decode.Pipeline
     exposing
         ( custom
         , optional
         , required
         )
-import Json.Encode as Encode
-    exposing
-        ( Value
-        , list
-        , object
-        )
+import Json.Encode as Encode exposing (Value)
 
 
 type alias Circle =
@@ -276,16 +236,16 @@ circleDecoder : Decoder Circle
 circleDecoder =
     succeed Circle
         |> required "center" Definitions.pointDecoder
-        |> optional "color" (nullable Definitions.colorDecoder) Nothing
+        |> optional "color" (Decode.nullable Definitions.colorDecoder) Nothing
         |> required "radius" Decode.float
 
 
 encodeCircle : Circle -> Value
 encodeCircle circle =
     []
-        |> encodeRequired "center" circle.center Definitions.encodePoint
-        |> encodeOptional "color" circle.color Definitions.encodeColor
-        |> encodeRequired "radius" circle.radius Encode.float
+        |> Encode.required "center" circle.center Definitions.encodePoint
+        |> Encode.optional "color" circle.color Definitions.encodeColor
+        |> Encode.required "radius" circle.radius Encode.float
         |> Encode.object
 ```
 
@@ -353,12 +313,9 @@ import Test exposing (..)
 
 colorFuzzer : Fuzzer Color
 colorFuzzer =
-    Fuzz.oneOf
-        [ Fuzz.constant Red
-        , Fuzz.constant Yellow
-        , Fuzz.constant Green
-        , Fuzz.constant Blue
-        ]
+    [ Red, Yellow, Green, Blue ]
+        |> List.map Fuzz.constant
+        |> Fuzz.oneOf
 
 
 encodeDecodeColorTest : Test
@@ -415,8 +372,9 @@ the following new directory structure is generated:
     ├── .tool-versions
     ├── package.json
     ├── elm.json
-    ├── tests/
+    ├── src/
     │   └── Data/
+    │       ├── Encode.elm
     │       ├── Circle.elm
     │       └── Definitions.elm
     └── tests/

config/config.exs

@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 config :elixir, ansi_enabled: true
 

config/dev.exs

@@ -1,3 +1,3 @@
-use Mix.Config
+import Config
 
 config :logger, level: :debug

config/prod.exs

@@ -1,3 +1,3 @@
-use Mix.Config
+import Config
 
 config :logger, level: :warn

config/test.exs

@@ -1,3 +1,3 @@
-use Mix.Config
+import Config
 
 config :logger, level: :debug

examples/example-input-json-schemas/definitions.json

@@ -1,26 +1,26 @@
 {
-    "$schema": "http://json-schema.org/draft-07/schema#",
-    "$id": "http://example.com/definitions.json",
-    "title": "Definitions",
-    "description": "Schema for common types",
-    "definitions": {
-        "color": {
-            "$id": "#color",
-            "type": "string",
-            "enum": [ "red", "yellow", "green", "blue" ]
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "http://example.com/definitions.json",
+  "title": "Definitions",
+  "description": "Schema for common types",
+  "definitions": {
+    "color": {
+      "$id": "#color",
+      "type": "string",
+      "enum": [ "red", "yellow", "green", "blue" ]
+    },
+    "point": {
+      "$id": "#point",
+      "type": "object",
+      "properties": {
+        "x": {
+          "type": "number"
         },
-        "point": {
-            "$id": "#point",
-            "type": "object",
-            "properties": {
-                "x": {
-                    "type": "number"
-                },
-                "y": {
-                    "type": "number"
-                }
-            },
-            "required": [ "x", "y" ]
+        "y": {
+          "type": "number"
         }
+      },
+      "required": [ "x", "y" ]
     }
+  }
 }

examples/example-output-elm-code/.tool-versions

@@ -1,2 +1,2 @@
-elm 0.19.0
+elm 0.19.1
 node 8.12.0

examples/example-output-elm-code/elm.json

@@ -1,28 +1,32 @@
 {
-    "type": "application",
-    "source-directories": [
-        "src"
-    ],
-    "elm-version": "0.19.0",
-    "dependencies": {
-        "direct": {
-            "NoRedInk/elm-json-decode-pipeline": "1.0.0",
-            "elm/browser": "1.0.1",
-            "elm/core": "1.0.0",
-            "elm/html": "1.0.0",
-            "elm/json": "1.0.0"
-        },
-        "indirect": {
-            "elm/random": "1.0.0",
-            "elm/time": "1.0.0",
-            "elm/url": "1.0.0",
-            "elm/virtual-dom": "1.0.2"
-        }
+  "type": "application",
+  "source-directories": [
+    "src"
+  ],
+  "elm-version": "0.19.1",
+  "dependencies": {
+    "direct": {
+      "NoRedInk/elm-json-decode-pipeline": "1.0.0",
+      "elm/browser": "1.0.1",
+      "elm/core": "1.0.0",
+      "elm/html": "1.0.0",
+      "elm/json": "1.0.0",
+      "elm-community/json-extra": "4.3.0"
     },
-    "test-dependencies": {
-        "direct": {
-            "elm-explorations/test": "1.2.0"
-        },
-        "indirect": {}
+    "indirect": {
+      "elm/parser": "1.1.0",
+      "elm/time": "1.0.0",
+      "elm/url": "1.0.0",
+      "elm/virtual-dom": "1.0.2",
+      "rtfeldman/elm-iso8601-date-strings": "1.1.4"
     }
+  },
+  "test-dependencies": {
+    "direct": {
+      "elm-explorations/test": "1.2.0"
+    },
+    "indirect": {
+      "elm/random": "1.0.0"
+    }
+  }
 }