add Track.parseFile and call it from the main app

that's right, this is no longer a hello world app

README.md

@@ -61,3 +61,6 @@ _Do not look below this line_
 * [done] need a real gpx file with namespace decls before we can parse power and stuff
 * [done] tests seem to pass without <gpx> element?
 * [done] stop returning bogus data when missing required elements (e.g. time)
+* can we lose this "if isJust lat && isJust lon && isJust ts" wart?
+* probably we should store points in a more efficient form than
+ a singly-linked list

app/Main.hs

@@ -1,4 +1,10 @@
 module Main where
 
+import Control.Exception
+import Track(parseFile)
+import Data.List as List
+
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+  points <- Track.parseFile "track.gpx"
+  putStrLn ("loaded " ++ (show (List.length points)))

lib/Track.hs

@@ -10,6 +10,7 @@ module Track
     heartRate,
     time,
     parse,
+    parseFile,
     Track.length,
   )
 where
@@ -20,6 +21,7 @@ import Data.List as List
 import Data.List qualified
 import Data.Map as Map
 import Data.Maybe
+import Data.Either
 import Data.Text qualified
 import Data.Text.Lazy as T
 import Data.Time
@@ -110,3 +112,10 @@ parse str = do
 
 length :: Track -> Int
 length = Data.List.length
+
+-- parseFile :: FilePath -> IO [Point]
+parseFile name = do
+  gpx <- Text.XML.readFile def name
+  return $ case getPoints (fromDocument gpx) of
+    Left err -> []
+    Right points -> points

souplesse.cabal

@@ -68,7 +68,9 @@ executable souplesse
     -- other-extensions:
 
     -- Other library packages from which modules are imported.
-    build-depends:    base ^>=4.18.2.1
+    build-depends:
+        base ^>=4.18.2.1
+      , souplesse-lib
 
     -- Directories containing source files.
     hs-source-dirs:   app