Include<T, U>
A more inclusive complement to TypeScript's
Exclude
helper type - only include the parts of a union type that are assignable to
another type.
typescriptjavascript
export type Include<T, U> = T extends U ? T : neverexport {}Usage
typescriptjavascript
type OpenAIMessage =
| {
role: 'user'
content: string
}
| {
role: 'ai'
content?: string
function_call?: {
name: string
arguments: string
}
}
/**
* This type is now only the user part of the message.
*/
type UserMessage = Include<OpenAIMessage, { role: 'user' }>