Add part8

intro/part8/src/Timestamp.elm

@@ -0,0 +1,100 @@
+module Timestamp exposing (format, iso8601Decoder, view)
+
+import Html exposing (Html, span, text)
+import Html.Attributes exposing (class)
+import Iso8601
+import Json.Decode as Decode exposing (Decoder, fail, succeed)
+import Time exposing (Month(..))
+
+
+
+-- VIEW
+
+
+view : Time.Zone -> Time.Posix -> Html msg
+view timeZone timestamp =
+    span [ class "date" ] [ text (format timeZone timestamp) ]
+
+
+
+-- DECODE
+
+
+{-| Decode an ISO-8601 date string.
+-}
+iso8601Decoder : Decoder Time.Posix
+iso8601Decoder =
+    Decode.string
+        |> Decode.andThen fromString
+
+
+fromString : String -> Decoder Time.Posix
+fromString str =
+    case Iso8601.toTime str of
+        Ok successValue ->
+            succeed successValue
+
+        Err _ ->
+            fail ("Invalid date: " ++ str)
+
+
+
+-- FORMAT
+
+
+{-| Format a timestamp as a String, like so:
+
+    "February 14, 2018"
+
+For more complex date formatting scenarios, here's a nice package:
+<https://package.elm-lang.org/packages/ryannhg/date-format/latest/>
+
+-}
+format : Time.Zone -> Time.Posix -> String
+format zone time =
+    let
+        month =
+            case Time.toMonth zone time of
+                Jan ->
+                    "January"
+
+                Feb ->
+                    "February"
+
+                Mar ->
+                    "March"
+
+                Apr ->
+                    "April"
+
+                May ->
+                    "May"
+
+                Jun ->
+                    "June"
+
+                Jul ->
+                    "July"
+
+                Aug ->
+                    "August"
+
+                Sep ->
+                    "September"
+
+                Oct ->
+                    "October"
+
+                Nov ->
+                    "November"
+
+                Dec ->
+                    "December"
+
+        day =
+            String.fromInt (Time.toDay zone time)
+
+        year =
+            String.fromInt (Time.toYear zone time)
+    in
+    month ++ " " ++ day ++ ", " ++ year