Function when

when<T>(validator, callback): ((input) => void)
Call a callback when validation succeeds
Type Parameters
- T
  The validated type
Parameters
- validator: Validator<T>
  The validator to use
- callback: ((t) => void)
  The callback to call
  - - (t): void
    - Parameters
      t: T
      Returns void
Returns ((input) => void)
- - (input): void
  - Parameters
    - input: unknown
    Returns void
Example
```
when(isNumber, () => {...})
```
- Defined in services/results.ts:160