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

[Joel Reymont]

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

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