#isOk

Type guard that narrows a Result to Ok.

if (isOk(result)) {
  // result.value is T
}

#Usage

#isOk(result)

isOk is how you discriminate a Result in TypeScript — inside the truthy branch, result.value is T; in the falsy branch, result is Err and result.error is Error.

import { attempt, isOk } from 'massaman'

const parsed = attempt(() => JSON.parse(input))
if (isOk(parsed)) {
  console.log(parsed.value) // narrowed to T
} else {
  console.error(parsed.error) // narrowed to Error
}

For pattern matching across both branches, prefer match with P.ok / P.err — it's exhaustive and reads better with multi-arm logic.

#Parameters

#Returns

true if the result is a success.

result is Ok<T>

#See also

• isErr — the inverse guard
• unwrap — extract the value or throw
• P.ok — pattern value for match
• Result & Errors concept guide