r2r-dev / difftastic

a syntax-aware diff

Difftastic is an experimental structured diff tool that compares files based on their syntax.

See the manual to get started.

Screenshots

Languages

Difftastic supports the following languages:

• C
• C++
• C#
• Clojure
• CSS
• Elixir
• Emacs Lisp
• Go
• Haskell
• Java
• JavaScript (and JSX)
• JSON
• OCaml
• Python
• Rust
• TypeScript (and TSX)

If a file has an unrecognised extension, difftastic uses a line-oriented diff.

Known Issues

Performance. Difftastic scales relatively poorly on files with a large number of changes, and can use a lot of memory. This might be solved by A* search.

Display. Difftastic has a side-by-side display which usually works well, but can be confusing.

Diff accuracy. Some delimiter moves are currently ignored (see #30).

Integration. Difftastic only has limited support for git and mercurial today.

Non-goals

Patch files. If you want to create a patch that you can later apply, use diff. Difftastic ignores whitespace, so its output is lossy. (AST patching is also a hard problem.)

License

Difftastic is open source under the MIT license, see LICENSE for more details.

Files in sample_files/ are also under the MIT license unless stated otherwise in their header.

Further Reading

The wiki includes additional notes on alternative diffing techniques and tools.