Skip to main content

Async Call Stacks

Asynchronous operations maintain separate call stacks for error propagation.

Why this exists​

Async call stacks preserve error context across await boundaries, enabling proper debugging.

How it works​

Each async operation has its own stack frame. When an error occurs, the stack trace includes all async frames leading to the error.

Examples​

fn level3() {
  throw "Error at level 3"
}

fn level2() {
  return await level3()
}

fn level1() {
  return await level2()
}

try {
  await level1()
} catch error {
  say "Caught error: " + error
  # Stack trace shows: level3 -> level2 -> level1
}

Common mistakes​

  • Not understanding stack traces in async code
  • Losing error context across await points