Hello Neil, Tuesday, February 5, 2008, 1:11:47 PM, you wrote: > insert x y = delete x > >>> deleteR y > >>> unsafeInsert x y i use the following trick: (.$) = flip ($) insert x y it = it.$ delete x .$ deleteR y .$ unsafeInsert x y -- Best regards, Bulat mailto:Bulat.Ziganshin at gmail.com