extend conformability to empty arrays

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/Data/Packed/Internal/Common.hs b/lib/Data/Packed/Internal/Common.hs
index 49f17b0..edef3c2 100644
--- a/lib/Data/Packed/Internal/Common.hs
+++ b/lib/Data/Packed/Internal/Common.hs
@@ -49,7 +49,11 @@ common f = commonval . map f where
 compatdim :: [Int] -> Maybe Int
 compatdim [] = Nothing
 compatdim [a] = Just a
-compatdim (a:b:xs) = if a==b || a==1 || b==1 then compatdim (max a b:xs) else Nothing
+compatdim (a:b:xs)
+    | a==b = compatdim (b:xs)
+    | a==1 = compatdim (b:xs)
+    | b==1 = compatdim (a:xs)
+    | otherwise = Nothing
 
 -- | Formatting tool
 table :: String -> [[String]] -> String