Patdiff is an OCaml implementation of Bram Cohen's patience diff algorithm, with a few extra conveniences for comparing code and config files:

outputs plain ASCII, ANSI color codes, or HTML

optional semantic diffing of numbers

good word-level diffing out of the box

And of course all the usual features:

• recursive diffing of directories
• extensively configurable output (markers, colors, location format, context)
• whitespace-aware diffing

opam install patdiff

See here for Patdiff's opam package file.

To build patdiff for local development, install its dependencies:

git clone https://github.com/janestreet/patdiff
cd patdiff
opam install --deps-only .

To compile, and optionally install, patdiff:

make
make install

patdiff old-file new-file

If you don't supply any arguments to patdiff, it will read diff-like text from stdin and color it in the normal patdiff way.

The file ~/.patdiff is used as a config file if it exists. You can write a sample config with the -make-config flag.

A simple wrapper is provided for using patdiff as git's "external diff" tool. You can enable it with:

export GIT_EXTERNAL_DIFF=$(command -v patdiff-git-wrapper)

or

git config --global diff.external $(command -v patdiff-git-wrapper)

More docs, including detailed API docs, are available here.