Kernel
- Dart course
- Expert
- Lesson 9/47
- 5 min
Learn Dart Kernel and intermediate representation.
Kernel
Kernel is Dart's platform-independent intermediate representation (IR). It is produced from the AST and can be serialized as a .dill file. Kernel is the common input to all backends.
Kernel is in binary form; loading is fast. Kernel fully represents the language semantics: types, generics, nullability, metadata. When a Kernel file is loaded, the backend only does code generation; no parse/type check is needed again.
The binary form advantage
Since Kernel is in binary form, it loads much faster than text-based source code. This matters especially for large projects and incremental compilation. The dart run command uses cached .dill files.
Kernel is also the verified form of the language: type checking is done, semantic analysis is complete. Backends take this verified form and focus only on code generation. This reduces compile time.
Practice A KernelModule class
Define a KernelModule class with final String name; final bool verified; KernelModule(this.name, this.verified); field and constructor. Add a String status() => verified ? 'verified' : 'pending'; method. In main create final m = KernelModule('myapp', true);; print with print(m.status());.
Starter code
void main() {
// define a KernelModule class (name, verified; status method)
// create a KernelModule; print status()
}Sample solution
class KernelModule {
final String name;
final bool verified;
KernelModule(this.name, this.verified);
String status() => verified ? 'verified' : 'pending';
}
void main() {
final m = KernelModule('myapp', true);
print(m.status());
}Expected output
verified
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the Kernel parts
| Term | Meaning |
|---|---|
Kernel |
Intermediate (IR) |
.dill |
Binary file |
AST |
Previous stage |
Backend |
Next stage |
2 What is Kernel used for?
- Only for documentation
- As a platform-independent IR Correct answer
- For garbage collection
- For UI rendering
Explanation: Kernel is the platform-independent IR that goes to all backends.
3 A .dill file
final kernelFile = '____';
print(kernelFile);final kernelFile = 'myapp.dill';
print(kernelFile);Explanation: .dill is the binary file extension for Kernel.