# is

`import { is } from "destack:schema";`

Return true when `value` satisfies `schema`.

```ds title="is"
export function is<T>(schema: &'a readonly Schema<T>, value: unknown): boolean
```

[language/library/src/schema/schema.ds:238:240](https://github.com/destack-sh/destack/blob/main/language/library/src/schema/schema.ds#L238-L240)