>>> splitWhen (<0) [1,3,-4,5,7,-9,0,2] [[1,3],[5,7],[0,2]]
>>> splitWhen (<0) [1,-2,3,4,-5,-6,7,8,-9] [[1],[3,4],[],[7,8],[]]
>>> splitWhen (<0) (BV.fromList [1,3,-4,5,7,-9,0,2]) [[1,3],[5,7],[0,2]]