difftastic

<p align="center">
  <a href="#readme"><img src="img/logo.png" alt="it's difftastic!"/></a>
  <br>
  <a href="https://difftastic.wilfred.me.uk/introduction.html"><img src="https://img.shields.io/badge/manual-en-brightgreen?style=plastic" alt="English manual"></a>
  <a href="https://difftastic.wilfred.me.uk/zh-CN/"><img src="https://img.shields.io/badge/manual-zh--CN-brightgreen?style=plastic" alt="Chinese manual"></a>
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</p>

Difftastic is a structural diff tool that compares files based on
their syntax.

**For installation instructions, see
[Installation](https://difftastic.wilfred.me.uk/installation.html) in
[the manual](https://difftastic.wilfred.me.uk/).**

## Examples

![Screenshot of difftastic and Rust](img/wrap_expr.png)

^ Difftastic understands exactly which pieces of syntax have changed,
and can highlight them in context.

![Screenshot of difftastic and HTML](img/html.png)

^ Difftastic understands when whitespace matters, and when it's just
an indentation change.

![Screenshot of difftastic and JS](img/reformat.png)

^ Difftastic is not line-oriented. If you reformat your code and it's
now split over multiple lines, difftastic will show you what's
actually changed.

![Screenshot of difftastic and git](img/git.png)

^ Difftastic is compatible with git (see [the configuration
instructions](https://difftastic.wilfred.me.uk/git.html)), as well as
many other version control systems.

## Languages Supported

Difftastic supports over 30 programming languages, see [the
manual](https://difftastic.wilfred.me.uk/languages_supported.html) for the full list.

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

## 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.

(Patch files are also line-oriented, which is too limited for
difftastic. Difftastic might find additions and removals on the same
line, and it tracks the relationship between line numbers in the old
and new file.)

Merging. AST merging is a hard problem that difftastic does not
address. You might be interested in the [mergiraf
tool](https://mergiraf.org/) ("merge giraffe"), which does do AST
merging.

## FAQ

### Can I use difftastic with git?

You can! The difftastic manual [includes instructions for git
usage](https://dif