Effect.ts: Absence as First-Class

3. Failure Effect

An effect that always fails - modeling absence through explicit failure

const fail = Effect.fail("Not found!");

// Effect<never, string, never>
//        ^^^^^  ^^^^^^
//        Never succeeds
//               Fails with string

try {
  await Effect.runPromise(fail);
} catch (error) {
  console.log(error); // "Not found!"
}

Failure = Typed unavailability through explicit absence.

Traditional code assumes values exist, then crashes when they don't. Effect TYPES the unavailability:

• Effect<never, string, never> says "this will NEVER be available"
• The error type (string) describes WHY it's unavailable
• No assumptions: we explicitly model "this data doesn't exist"

This is the core philosophy: don't assume data exists. Type its absence.

Part 3 of 51 in the Effect.ts Absence Modeling series