O | /src/option/mod.ts | ahh@v0.9.1

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Idiomatic type-safety structures for TypeScript.

method O.expect

import { O } from "https://deno.land/x/ahh@v0.9.1/src/option/mod.ts";

expect<T>(o: Option<T>, message: string): o extends Some<T> ? T : never

Returns the contained Some value.

Throws if the Option is a None with the provided message.

Examples

import { O, None } from "./mod.ts";

console.log(O.expect(1, "returns")); // 1
O.expect(None, "throws"); // throws

message: string

o extends Some<T> ? T : never