pkg/kernel/README.md

Dart Kernel
===========
**Dart Kernel** is a small high-level language derived from Dart.
It is designed for use as an intermediate format for whole-program analysis
and transformations, and as a frontend for codegen and execution backends.

The kernel language has in-memory representations in Dart and C++, and
can be serialized as binary or text.

Both the kernel language and its implementations are unstable and are under development.

This package contains the Dart part of the implementation and contains:
- A transformable IR for the kernel language
- A frontend based on the analyzer
- Serialization of kernel code

_Note:_ The APIs in this package are in an early state; developers should be
careful about depending on this package.  In particular, there is no semver
contract for release versions of this package.  Please depend directly
on individual versions.

Getting Kernel
------------

Checkout the repository and run pub get:
```bash
git clone https://github.com/dart-lang/kernel
cd kernel
pub get
```

Command-Line Tool
-----------------

Run `tool/dartk.dart` from the command-line to convert between .dart files
and the serialized binary and textual formats.

`dartk` expects the `.dill` extension for files in the binary format.
The textual format has no preferred extension right now.

Example commands:
```bash
dartk foo.dart            # print text IR for foo.dart
dartk foo.dart -ofoo.dill # write binary IR for foo.dart to foo.dill
dartk foo.dill            # print text IR for binary file foo.dill
```

Pass the `--link` or `-l` flag to link all transitive dependencies into one file:
```bash
dartk myapp.dart -ppackages -l -omyapp.dill # Bundle everything.
dartk myapp.dill # Print it back out in a (very, very long) textual format.
```

See [ast.dart](lib/ast.dart) for the in-memory IR, or [binary.md](binary.md) for
a description of the binary format.  For now, the textual format is very ad-hoc
and cannot be parsed back in.


Testing
-------

If you plan to make changes to kernel, get a checkout of the Dartk SDK and run:
```bash
tool/regenerate_dill_files.dart --sdk <path to SDK checkout>
pub run test
```


Linking
-------------------------
Linking from binary files is not yet implemented.  In order to compile a whole
program, currently everything must be compiled from source at once.