Diffing of (expression) trees.

Diffing arbitrary Haskell data. First we convert values to untyped haskell-like expression Expr using generically derivable ToExpr class. Then we can diff two Expr values. The conversion and diffing is done by ediff function. See type and function haddocks for an examples.

Interesting modules:

• Data.TreeDiff.Class for a ToExpr class and ediff utility.
• Data.TreeDiff.Golden for golden tests helper
• Data.TreeDiff.QuickCheck for QuickCheck helper