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Reasoning about effects: seeing the wood through the trees
Graham Hutton and Diana Fulger. To be presented at the Symposium on Trends in Functional Programming, May 2008.
Pure functional languages such as Haskell support programming with impure effects by exploiting mathematical notions such as monads, applicative functors, and arrows. However, in contrast to the wealth of research on the use of these notions to write effectful programs, there has been comparatively little progress on reasoning about the resulting programs. In this article we focus on this problem, using a simple but instructive example concerned with relabelling binary trees.