From 800b8907c8d25434c98e522ae8f6d5a49b5c28e5 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Mon, 12 Mar 2018 11:27:06 +0200
Subject: [PATCH] Better parse error messages #252

---
 src/Stackage/Database.hs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/Stackage/Database.hs b/src/Stackage/Database.hs
index 60fb635..17642df 100644
--- a/src/Stackage/Database.hs
+++ b/src/Stackage/Database.hs
@@ -65,7 +65,7 @@ import Stackage.Types
 import Stackage.Metadata
 import Stackage.PackageIndex.Conduit
 import Web.PathPieces (fromPathPiece)
-import Data.Yaml (decodeFileEither)
+import Data.Yaml (decodeFileEither, decodeEither)
 import Database.Persist
 import Database.Persist.Postgresql
 import Database.Persist.TH
@@ -316,7 +316,13 @@ getPackageId x = do
 addPackage :: Tar.Entry -> SqlPersistT (ResourceT IO) ()
 addPackage e =
     case ("packages/" `isPrefixOf` fp && takeExtension fp == ".yaml", Tar.entryContent e) of
-        (True, Tar.NormalFile lbs _) | Just pi <- decode $ toStrict lbs -> do
+        (True, Tar.NormalFile lbs _) ->
+          case decodeEither $ toStrict lbs of
+            Left err -> putStrLn $ "ERROR: Could not parse " ++ tshow fp ++ ": " ++ tshow err
+            Right pi -> onParse pi
+        _ -> return ()
+  where
+    onParse pi = do
             let p = Package
                     { packageName = pack base
                     , packageLatest = display $ piLatest pi
@@ -341,8 +347,7 @@ addPackage e =
                 , depUses = display uses
                 , depRange = display range
                 }
-        _ -> return ()
-  where
+
     fp = Tar.entryPath e
     base = takeBaseName fp