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

See the manual to get started.

Demo 1: Wrapping Expressions

Difftastic understands expression nesting. If you wrap an expression in an if statement, difftastic understands that the inner values are unchanged.

Compare this with git's default diff. It is confused by indentation changes, and doesn't know which closing parenthesis has been added.

Demo 2: Reflowing Code

Difftastic is robust to code formatting changes. If you change how many items appear on a single line, difftastic will only show you items which have changed.

In git's default diff, it's harder to see that iter and the curly braces are unchanged. It's also harder to see the affected line numbers.

Languages

Difftastic supports the following languages:

• Bash
• C
• C++
• C#
• Clojure
• Common Lisp
• CSS
• Elixir
• Emacs Lisp
• Go
• Haskell
• Java
• JavaScript (and JSX)
• JSON
• OCaml
• PHP
• Python
• Ruby
• Rust
• Scala
• 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.

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

Robustness. Difftastic regularly has releases that fix crashes.

Non-goals

Patching. Difftastic output is intended for human consumption, and it does not generate patches that you can apply later. Use diff if you need a patch.

Merging. AST merging is a hard problem that difftastic does not address.

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.