bahnhof-name: more lenient parsing of OSM responsesrnv

Cassava's (.!) throws exceptions on missing fields even if there's a
reasonable default value. Shouldn't do that anymore.

1 files changed, 7 insertions, 6 deletions

diff --git a/app/Main.hs b/app/Main.hs
index 0f2e3e7..0c004d5 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -50,12 +50,13 @@ instance FromRecord Platform where
     Platform <$>
       v .! 0 <*>
       v .! 1 <*>
-      v .! 2 <*>
-      v .! 3 <*>
-      (v .! 4 <|> v .! 5) <*>
-      v .! 6 <*>
-      v .! 7 <*>
-      v .! 8
+      v .!? 2 <*>
+      v .!? 3 <*>
+      (v .!? 4 <|> v .!? 5) <*>
+      v .!? 6 <*>
+      v .!? 7 <*>
+      v .!? 8
+    where v .!? b = fromMaybe (pure Nothing) $ fmap parseField (v V.!? b)
 
 data Answer
   = Redirect Text