[Haskell-cafe] Arrows for invertible programming: Notation question

Folks, I have been looking at the code for the "Arrows for invertible programming" paper (http://www.cs.ru.nl/A.vanWeelden/bi-arrows/) and I have a question about syntax. ghci surely does not like it. What does this mean and how do I make it compile? mapl{|a, b|arr|} :: (mapl{|a, b|arr|}, ArrowChoice arr, BiArrow arr) => arr a b Thanks, Joel -- http://wagerlabs.com/