Rename more stuff

intro/part1/src/Data/Article.elm

@@ -0,0 +1,154 @@
+module Data.Article
+    exposing
+        ( Article
+        , Body
+        , Slug
+        , Tag
+        , bodyToHtml
+        , bodyToMarkdownString
+        , decoder
+        , decoderWithBody
+        , slugParser
+        , slugToString
+        , tagDecoder
+        , tagToString
+        )
+
+import Data.Article.Author as Author exposing (Author)
+import Date exposing (Date)
+import Html exposing (Attribute, Html)
+import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Extra
+import Json.Decode.Pipeline exposing (custom, decode, hardcoded, required)
+import Markdown
+import UrlParser
+
+
+{-| An article, optionally with an article body.
+
+To see the difference between { body : body } and { body : Maybe Body },
+consider the difference between the "view individual article" page (which
+renders one article, including its body) and the "article feed" -
+which displays multiple articles, but without bodies.
+
+This definition for `Article` means we can write:
+
+viewArticle : Article Body -> Html msg
+viewFeed : List (Article ()) -> Html msg
+
+This indicates that `viewArticle` requires an article _with a `body` present_,
+wereas `viewFeed` accepts articles with no bodies. (We could also have written
+it as `List (Article a)` to specify that feeds can accept either articles that
+have `body` present or not. Either work, given that feeds do not attempt to
+read the `body` field from articles.)
+
+This is an important distinction, because in Request.Article, the `feed`
+function produces `List (Article ())` because the API does not return bodies.
+Those articles are useful to the feed, but not to the individual article view.
+
+-}
+type alias Article a =
+    { description : String
+    , slug : Slug
+    , title : String
+    , tags : List String
+    , createdAt : Date
+    , updatedAt : Date
+    , favorited : Bool
+    , favoritesCount : Int
+    , author : Author
+    , body : a
+    }
+
+
+
+-- SERIALIZATION --
+
+
+decoder : Decoder (Article ())
+decoder =
+    baseArticleDecoder
+        |> hardcoded ()
+
+
+decoderWithBody : Decoder (Article Body)
+decoderWithBody =
+    baseArticleDecoder
+        |> required "body" bodyDecoder
+
+
+baseArticleDecoder : Decoder (a -> Article a)
+baseArticleDecoder =
+    decode Article
+        |> required "description" (Decode.map (Maybe.withDefault "") (Decode.nullable Decode.string))
+        |> required "slug" (Decode.map Slug Decode.string)
+        |> required "title" Decode.string
+        |> required "tagList" (Decode.list Decode.string)
+        |> required "createdAt" Json.Decode.Extra.date
+        |> required "updatedAt" Json.Decode.Extra.date
+        |> required "favorited" Decode.bool
+        |> required "favoritesCount" Decode.int
+        |> required "author" Author.decoder
+
+
+
+-- IDENTIFIERS --
+
+
+type Slug
+    = Slug String
+
+
+slugParser : UrlParser.Parser (Slug -> a) a
+slugParser =
+    UrlParser.custom "SLUG" (Ok << Slug)
+
+
+slugToString : Slug -> String
+slugToString (Slug slug) =
+    slug
+
+
+
+-- TAGS --
+
+
+type Tag
+    = Tag String
+
+
+tagToString : Tag -> String
+tagToString (Tag slug) =
+    slug
+
+
+tagDecoder : Decoder Tag
+tagDecoder =
+    Decode.map Tag Decode.string
+
+
+
+-- BODY --
+
+
+type Body
+    = Body Markdown
+
+
+type alias Markdown =
+    String
+
+
+bodyToHtml : Body -> List (Attribute msg) -> Html msg
+bodyToHtml (Body markdown) attributes =
+    Markdown.toHtml attributes markdown
+
+
+bodyToMarkdownString : Body -> String
+bodyToMarkdownString (Body markdown) =
+    markdown
+
+
+bodyDecoder : Decoder Body
+bodyDecoder =
+    Decode.map Body Decode.string