Result union type in TypeScript

A discriminated union for success or failure, so errors are values the compiler checks.

type Ok<T> = { ok: true; value: T };
type Err = { ok: false; error: string };
type Result<T> = Ok<T> | Err;

function unwrap<T>(result: Result<T>): T {
  if (result.ok) {
    return result.value;
  }
  throw new Error(result.error);
}

Keywords and builtins used here

• Result
• T
• false
• function
• if
• return
• string
• throw
• true
• type

The run, in numbers

Lines

10

Characters to type

224

Tokens

81

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 46 seconds.

Type this snippet

Step 2 of 4 in Results & validation, step 6 of 19 in Classes & patterns.

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