better Show instance for Time

1 files changed, 7 insertions, 3 deletions

diff --git a/lib/GTFS.hs b/lib/GTFS.hs
index 17dec72..9259649 100644
--- a/lib/GTFS.hs
+++ b/lib/GTFS.hs
@@ -92,9 +92,13 @@ instance CSV.FromField Time where
 
 instance Show Time where
   show (Time seconds) = ""
-    +|seconds `div` 3600|+":"
-    +|(seconds `mod` 3600) `div` 60|+":"
-    +|seconds `mod` 60|+""
+    +|pad (seconds `div` 3600)|+":"
+    +|pad ((seconds `mod` 3600) `div` 60)|+
+    if seconds `mod` 60 /= 0 then ":"+|pad (seconds `mod` 60)|+""
+    else ""
+    where pad num =
+            if length str < 2 then "0"<>str else str
+            where str = show num
 
 instance CSV.FromField Day where
   parseField f = do