Fix issues in number of pieces property

1 files changed, 4 insertions, 2 deletions

diff --git a/test/Test.hs b/test/Test.hs
index 7155d84..6741e70 100644
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE TemplateHaskell, ParallelListComp #-}
 -- vim: sw=2 ts=2 et ai:
 module Test where
 
@@ -29,7 +29,9 @@ atAnyState ok pgn = and [ok b | Right b <- seqList [moveSAN m | m <- moves pgn]
     seqList []     _          = []
 
 atAnyTwoStates :: (Board -> Board -> Bool) -> PGN -> Bool
-atAnyTwoStates ok pgn = and [ok b1 b2 | Right b1 <- seqList [moveSAN m | m <- moves pgn] | Right b2 <- seqList [moveSAN m | m <- moves pgn] $ Right defaultBoard]
+atAnyTwoStates ok pgn =
+  let moveList = seqList [moveSAN m | m <- moves pgn] $ Right defaultBoard in
+  and [ok b1 b2 | Right b1 <- moveList | Right b2 <- tail moveList]
   where
     seqList :: [r -> Either e r] -> Either e r -> [Either e r]
     seqList (f:fs) (Right io) = f io:seqList fs (f io)