Difftastic is an experimental structured diff tool that compares files based on their syntax.
See the manual to get started.
Difftastic supports the following languages:
- Clojure
- CSS
- Elixir
- Emacs Lisp
- Go
- 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
Robustness. Difftastic is young and each release has fixed several crashes.
Comprehensible display. Minimal diffs can be confusing: replacing one function with another may have a small amount of common punctuation even though they're completely unrelated. Alignment of slightly modified lines is a major challenge too.
Changes to long lines. Difftastic uses a side-by-side display by default, which is unhelpful if the only changes are near the end of a line.
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.
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 a thorough overview of alternative diffing techniques and tools.