AgentScript Effect Examples

Error Handling Examples

AgentScript

function maybeCompute(value: number): number
  goal: "Demonstrates random failure for example"
  requires:
    value >= 0: "Value must be non-negative"
  return:
    value
      |> randomTrigger
      |> finalizeCompute

  errors:
    CustomError: "Oops, random event occurred"

  tests:
    success:
      10 -> 10
    errors:
      0 -> CustomError`

TypeScript (Effect)

import { Console, Effect } from 'effect'

class CustomError {
  readonly _tag = 'CustomError'
  constructor(readonly value: number) {}
}

const maybeFail: Effect.Effect<number, CustomError> = Effect.sync(() => Math.random()).pipe(
  Effect.andThen((value) =>
    value > 0.5
      ? Effect.fail(new CustomError(value))
      : Effect.succeed(value)
  ),
)

const main = maybeFail.pipe(
  Effect.andThen((value) => Console.log(`Got value \${value}`)),
  Effect.catchTag('CustomError', (error) => Console.error(`Oops! Got value ${error.value}`)),
)

Effect.runPromise(main)

TypeScript (Plain)

class CustomError extends Error {
  constructor(readonly value: number) {
    super(`Custom error triggered with value ${value}`)
  }
}

function maybeFail(): number {
  const value = Math.random()
  if (value > 0.5) {
    throw new CustomError(value)
  }
  return value
}

function main(): void {
  try {
    const result = maybeFail()
    console.log(`Got value ${result}`)
  } catch (error) {
    if (error instanceof CustomError) {
      console.error(`Oops! Got value ${error.value}`)
    } else {
      console.error('Unknown error occurred!')
    }
  }
}

main()`