Diffing of (expression) trees.

Common diff algorithm works on list structures:

diff :: Eq a => [a] -> [a] -> [Edit a]

This package works on trees.

treeDiff :: Eq a => Tree a -> Tree a -> Edit (EditTree a)

This package also provides a way to diff arbitrary ADTs, using Generics-derivable helpers.

This package differs from gdiff, in a two ways: tree-diff doesn't have patch function, and the "edit-script" is a tree itself, which is useful for pretty-printing.

>>> prettyEditExpr $ ediff (Foo 42 [True, False] "old") (Foo 42 [False, False, True] "new")
Foo
  {fooBool = [-True, +False, False, +True],
   fooInt = 42,
   fooString = -"old" +"new"}

tree-diff

Diffing of (expression) trees.

Examples

tree-diff displays pretty diffs of tree data:

Because of its untyped internal type, it copes with type changes:

As a bonus, multiline Strings and Text are diffed linewise: