add glue to serve frontend js from backend

Makefile

@@ -0,0 +1,7 @@
+default: frontend/frontend.js dist-newstyle/build/x86_64-linux/ghc-9.6.5/souplesse-0.1.0.0/x/souplesse/build/souplesse/souplesse
+
+dist-newstyle/build/x86_64-linux/ghc-9.6.5/souplesse-0.1.0.0/x/souplesse/build/souplesse/souplesse: app/*.hs lib/*.hs
+	cabal build
+
+frontend/frontend.js: frontend/src/Main.elm
+	elm make --output=$@ $<

app/Main.hs

@@ -2,6 +2,7 @@
 {-# LANGUAGE QuasiQuotes           #-}
 {-# LANGUAGE TemplateHaskell       #-}
 {-# LANGUAGE TypeFamilies          #-}
+
 module Main where
 
 import Track(parseFile)
@@ -9,19 +10,56 @@ import Data.List as List
 
 import           Yesod.Core
 
-data HelloWorld = HelloWorld
+-- https://github.com/yesodweb/yesod-cookbook/blob/master/cookbook/Static-file-subsite-Hello-World.md
+import Yesod.Static
+staticFiles "frontend" -- this param appears to be a pathname
 
-mkYesod "HelloWorld" [parseRoutes|
-/ HomeR GET
+data Souplesse = Souplesse
+  { getStatic :: Static
+  }
+
+-- ref https://www.yesodweb.com/book/routing-and-handlers
+-- for adding params (start/end) to the timeline route
+mkYesod "Souplesse" [parseRoutes|
+/ CalendarR GET
+/timeline TimelineR GET
+/static StaticR Static getStatic
 |]
 
-instance Yesod HelloWorld
+instance Yesod Souplesse
+
+getCalendarR :: Handler Html
+getCalendarR = defaultLayout [whamlet|
+<h1>Calendar</h1>
+
+<p>A calendar view goes here
+
+<a href="/timeline">timeline</a>
+&copy; 2024 Daniel Barlow
+|]
+
+getTimelineR :: Handler Html
+
+-- what's this about? <img src=@{StaticR image_png}/>|]
+getTimelineR = defaultLayout $ do
+  setTitle "timeline"
+  addScriptRemote "/static/frontend.js"
+  toWidgetBody [julius|
+window.addEventListener("load", function(){
+var app = Elm.Main.init({
+  node: document.getElementById("elm")
+});
+})
+|]
+  toWidget [hamlet|
+<pre id="elm">
+<p>Copyright &copy; 2024 Daniel Barlow
+|]
 
-getHomeR :: Handler Html
-getHomeR = defaultLayout [whamlet|Hello World!|]
 
 main :: IO ()
 main = do
   points <- Track.parseFile "track.gpx"
-  putStrLn ("loaded " ++ (show (List.length points)) ++ " points from GPX")
-  warp 3000 HelloWorld
+  static'@(Static settings) <- static "frontend"
+  putStrLn ("loaded " ++ show (List.length points) ++ " points from GPX")
+  warp 3000 $ Souplesse static'

souplesse.cabal

@@ -72,6 +72,7 @@ executable souplesse
         base ^>=4.18.2.1
       , souplesse-lib
       , yesod-core == 1.6.25.1
+      , yesod-static
 
     -- Directories containing source files.
     hs-source-dirs:   app