Configuration

Skittles is configured via a skittles.config.json or skittles.config.js file in your project root.

Config File

Create skittles.config.json:

skittles.config.json

{
  "contractsDir": "contracts",
  "outputDir": "build",
  "typeCheck": true,
  "optimizer": {
    "enabled": true,
    "runs": 200
  }
}

Or use JavaScript for dynamic configuration:

skittles.config.js

module.exports = {
  contractsDir: "contracts",
  outputDir: "build",
  typeCheck: true,
  optimizer: {
    enabled: process.env.NODE_ENV === "production",
    runs: 200,
  },
};

Options

Option	Type	Default	Description
contractsDir	string	"contracts"	Directory containing your TypeScript contract files
outputDir	string	"build"	Directory where compiled artifacts are written
typeCheck	boolean	true	Enable TypeScript type checking during compilation
optimizer.enabled	boolean	false	Enable the Solidity optimizer
optimizer.runs	number	200	Number of optimizer runs (higher = optimized for frequent calls)

Default Behavior

If no config file is found, Skittles uses these defaults:

{
  "contractsDir": "contracts",
  "outputDir": "build",
  "typeCheck": true,
  "optimizer": {
    "enabled": false,
    "runs": 200
  }
}

Optimizer

The optimizer setting controls the Solidity compiler's (solc) optimization pass. When enabled, it reduces gas costs for contract deployment and function execution.

• enabled: false (default): No optimization. Faster compilation, larger bytecode.
• enabled: true: Optimizes the generated bytecode for gas efficiency.
• runs: How many times each function is expected to be called. Lower values optimize for deployment cost, higher values optimize for execution cost. 200 is a good default for most contracts.

{
  "optimizer": {
    "enabled": true,
    "runs": 200
  }
}

Incremental Compilation

Skittles uses SHA256 based incremental compilation. A cache file (.skittles-cache.json) is stored in the output directory and tracks:

• The hash of each source file
• The hash of all shared definitions (types, functions, constants)

On subsequent compilations:

• If a file has not changed and no shared definitions have changed, the cached artifacts are reused
• If a file changed, only that file is recompiled
• If any shared definition changed (e.g., a struct in types.ts), all files that depend on shared definitions are recompiled

This keeps compilation fast even as your project grows. Use skittles clean to clear the cache and force a full recompilation.

TypeScript Configuration

Skittles reads TypeScript files directly using the TypeScript compiler API. You do not need a special tsconfig.json for Skittles, but having one gives you IDE support.

The skittles init command generates a tsconfig.json configured for contract development:

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "nodenext",
    "moduleResolution": "nodenext",
    "lib": ["ES2022"],
    "strict": true,
    "strictPropertyInitialization": false,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,
    "outDir": "./dist",
    "rootDir": "."
  },
  "include": ["contracts/**/*"],
  "exclude": ["node_modules", "build", "dist"]
}

Key settings:

• strictPropertyInitialization: false is important because state variables are initialized by the Solidity runtime, not in a constructor
• include should cover your contracts directory
• outDir and rootDir are only relevant if you also run the TypeScript compiler directly (not required for Skittles)