On Sun, Sep 21, 2014 at 9:02 PM, Derek McLoughlin <derek.mcloughlin@gmail.com> wrote:

I'm trying to get Graham Hutton's "Programming with Effects" article
(http://www.cs.nott.ac.uk/~gmh/monads) working with Data.Tree instead
of the Tree he provides.

Hi Derek,

This is a lovely problem that's inspired a bunch of interesting papers recently.

Here's a stab at the compilation error you're facing:

http://www.atamo.com/blog/how-to-solve-a-tricky-monad-problem-1/

Enjoy :)

-- Kim-Ee