handle-unexpected-errors-by-inspecting-the-cause

description: Use Cause to inspect, analyze, and handle all possible failure modes of an Effect, including expected errors, defects, and interruptions. globs: "**/*.ts" alwaysApply: true

Handle Unexpected Errors by Inspecting the Cause

Rule: Use Cause to inspect, analyze, and handle all possible failure modes of an Effect, including expected errors, defects, and interruptions.

Example

import { Cause, Effect } from "effect";

// An Effect that may fail with an error or defect
const program = Effect.try({
  try: () => {
    throw new Error("Unexpected failure!");
  },
  catch: (err) => err,
});

// Catch all causes and inspect them
const handled = program.pipe(
  Effect.catchAllCause((cause) =>
    Effect.sync(() => {
      if (Cause.isDie(cause)) {
        console.error("Defect (die):", Cause.pretty(cause));
      } else if (Cause.isFailure(cause)) {
        console.error("Expected error:", Cause.pretty(cause));
      } else if (Cause.isInterrupted(cause)) {
        console.error("Interrupted:", Cause.pretty(cause));
      }
      // Handle or rethrow as needed
    })
  )
);

Explanation:

• Cause distinguishes between expected errors (fail), defects (die), and interruptions.
• Use Cause.pretty for human-readable error traces.
• Enables advanced error handling and debugging.

Explanation:
Traditional error handling often loses information about why a failure occurred.
Cause preserves the full error context, enabling advanced debugging, error reporting, and robust recovery strategies.