Kernel

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.

Exercise 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());.

Show example 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());
}

Test yourself

Match the Kernel parts

Kernel

Intermediate (IR)
.dill

Binary file
AST

Previous stage
Backend

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What is Kernel used for?
- Only for documentation
- As a platform-independent IR
- For garbage collection
- For UI rendering
Show answer

As a platform-independent IR — Kernel is the platform-independent IR that goes to all backends.

A .dill file

final kernelFile = '____';
print(kernelFile);

Show answer

final kernelFile = 'myapp.dill';
print(kernelFile);

Next lesson: Code generation

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