Add distill helpers for codec packages.

elm.json

@@ -26,6 +26,7 @@
     ],
     "elm-version": "0.19.0 <= v < 0.20.0",
     "dependencies": {
+        "MartinSStewart/elm-serialize": "1.2.5 <= v < 2.0.0",
         "avh4/elm-color": "1.0.0 <= v < 2.0.0",
         "danyx23/elm-mimetype": "4.0.1 <= v < 5.0.0",
         "dillonkearns/elm-bcp47-language-tag": "1.0.1 <= v < 2.0.0",

examples/docs/src/Page/Blog/Slug_.elm

@@ -244,9 +244,8 @@ data route =
                         |> DataSource.fromResult
                 )
          )
-            |> DataSource.distill ("markdown-blocks-" ++ route.slug)
-                (S.encodeToJson (S.list MarkdownCodec.codec))
-                (S.decodeFromJson (S.list MarkdownCodec.codec) >> Result.mapError (\_ -> "Error"))
+            |> DataSource.distillSerializeCodec ("markdown-blocks-" ++ route.slug)
+                (S.list MarkdownCodec.codec)
             |> DataSource.andThen
                 (\blocks ->
                     blocks

examples/docs/src/Page/Docs/Section__.elm

@@ -157,12 +157,7 @@ titleForSection section =
                     |> Result.fromMaybe "Expected to find an H1 heading in this markdown."
                     |> DataSource.fromResult
             )
-        |> DataSource.distill ("next-previous-" ++ section.slug)
-            (Serialize.encodeToJson NextPrevious.serialize)
-            (Serialize.decodeFromJson
-                NextPrevious.serialize
-                >> Result.mapError (\_ -> "Error")
-            )
+        |> DataSource.distillSerializeCodec ("next-previous-" ++ section.slug) NextPrevious.serialize
 
 
 head :

examples/docs/src/TableOfContents.elm

@@ -32,9 +32,7 @@ dataSource docFiles =
             )
         |> DataSource.resolve
         |> DataSource.map List.reverse
-        |> DataSource.distill "table-of-contents"
-            (S.encodeToJson serialize)
-            (S.decodeFromJson serialize >> Result.mapError (\_ -> "Error"))
+        |> DataSource.distillSerializeCodec "table-of-contents" serialize
 
 
 codec : Codec (TableOfContents Data)

src/DataSource.elm

@@ -6,6 +6,7 @@ module DataSource exposing
     , andThen, resolve, combine
     , map2, map3, map4, map5, map6, map7, map8, map9
     , distill, validate
+    , distillCodec, distillSerializeCodec
     )
 
 {-| StaticHttp requests are an alternative to doing Elm HTTP requests the traditional way using the `elm/http` package.
@@ -66,6 +67,7 @@ and describe your use case!
 
 -}
 
+import Codec
 import Dict exposing (Dict)
 import Dict.Extra
 import Json.Decode as Decode
@@ -77,6 +79,7 @@ import Pages.Secrets
 import Pages.StaticHttp.Request as HashRequest
 import Pages.StaticHttpRequest exposing (RawRequest(..), WhatToDo)
 import RequestsAndPending exposing (RequestsAndPending)
+import Serialize
 
 
 {-| Build an empty body for a StaticHttp request. See [elm/http's `Http.emptyBody`](https://package.elm-lang.org/packages/elm/http/latest/Http#emptyBody).
@@ -237,6 +240,43 @@ distill uniqueKey encode decode dataSource =
                 )
 
 
+{-| -}
+distillSerializeCodec :
+    String
+    -> Serialize.Codec error value
+    -> DataSource value
+    -> DataSource value
+distillSerializeCodec uniqueKey serializeCodec =
+    distill uniqueKey
+        (Serialize.encodeToJson serializeCodec)
+        (Serialize.decodeFromJson serializeCodec
+            >> Result.mapError
+                (\error ->
+                    case error of
+                        Serialize.DataCorrupted ->
+                            "DataCorrupted"
+
+                        Serialize.CustomError errorMessage ->
+                            "CustomError"
+
+                        Serialize.SerializerOutOfDate ->
+                            "SerializerOutOfDate"
+                )
+        )
+
+
+{-| -}
+distillCodec :
+    String
+    -> Codec.Codec value
+    -> DataSource value
+    -> DataSource value
+distillCodec uniqueKey codec =
+    distill uniqueKey
+        (Codec.encodeToValue codec)
+        (Codec.decodeValue codec >> Result.mapError Decode.errorToString)
+
+
 toResult : Result Pages.StaticHttpRequest.Error ( Dict String WhatToDo, b ) -> RawRequest b
 toResult result =
     case result of