json-encode times as epoch seconds, as elm prefers

elm.json

@@ -10,6 +10,7 @@
             "elm/core": "1.0.5",
             "elm/html": "1.0.0",
             "elm/http": "2.0.0",
+            "elm/json": "1.1.3",
             "elm/svg": "1.0.1",
             "elm/time": "1.0.0",
             "elm-explorations/test": "2.2.0",
@@ -20,7 +21,6 @@
         "indirect": {
             "elm/bytes": "1.0.8",
             "elm/file": "1.0.5",
-            "elm/json": "1.1.3",
             "elm/parser": "1.1.0",
             "elm/random": "1.0.0",
             "elm/url": "1.0.0",

frontend/src/Main.elm

@@ -6,6 +6,7 @@ import Html.Attributes as H exposing (src, style, width, height)
 import Html.Events exposing (onClick)
 import Html.Events.Extra.Pointer as Pointer
 import Maybe exposing (Maybe)
+import Json.Decode as D
 import Http
 import Svg exposing (Svg, svg, rect, circle, g)
 import Svg.Attributes as S exposing

lib/Point.hs

@@ -24,6 +24,7 @@ import Debug.Trace (trace, traceShow)
 import Text.Read (readMaybe)
 import Text.XML
 import Text.XML.Cursor as Cursor
+import Data.Time.Clock.POSIX (posixSecondsToUTCTime, utcTimeToPOSIXSeconds)
 
 data Pos = Pos Double Double (Maybe Double) deriving (Show, Eq)
 
@@ -52,7 +53,7 @@ instance ToJSON Point where
   toJSON Point {..} =
     object
       [ "pos" .= pos,
-        "time" .= time,
+        "time" .= utcTimeToPOSIXSeconds time,
         "cadence" .= cadence,
         "power" .= power,
         "heartRate" .= heartRate