Custom Primitives

You can extend the built-in primitive types with your own semantic extensions via atscript.config.js. Custom primitives work exactly like built-in ones — they appear in IntelliSense, carry validation constraints, and generate appropriate type tags.

Defining Custom Extensions

Add custom extensions under the primitives key in your config:

import { defineConfig } from '@atscript/core'
import ts from '@atscript/typescript'

export default defineConfig({
  rootDir: 'src',
  plugins: [ts()],
  primitives: {
    string: {
      extensions: {
        url: {
          type: 'string',
          documentation: 'URL format',
          expect: {
            pattern: ['^https?://.+$', '', 'Invalid URL'],
          },
        },
        slug: {
          type: 'string',
          documentation: 'URL-safe slug',
          expect: {
            pattern: ['^[a-z0-9-]+$', '', 'Invalid slug'],
          },
        },
      },
    },
    number: {
      extensions: {
        percentage: {
          type: 'number',
          documentation: 'Percentage value (0–100)',
          expect: {
            min: 0,
            max: 100,
          },
        },
      },
    },
  },
})

Each extension object supports:

Field	Description
type	The base TypeScript type ('string', 'number', 'boolean')
documentation	Description shown in IntelliSense
expect	Implicit validation constraints — same keys as @expect.* annotations

Using Custom Primitives

Once defined, use them in .as files with dot notation:

export interface Page {
    url: string.url
    slug: string.slug
    completeness: number.percentage
}

The validator will automatically enforce the constraints defined in your config — no @expect.* annotations needed.

Re-generate after config changes

Run npx asc -f dts after adding custom primitives to regenerate atscript.d.ts. This updates IntelliSense with your new type tags. See Configuration for details.

Next Steps

• Primitives — built-in primitive types and semantic extensions
• Custom Annotations — define custom annotation types
• Configuration — full config file reference