Error Handling

etl4s provides built-in failure handling:

.withRetry

Retry failed operations with exponential backoff using .withRetry:

import etl4s._

var attempts = 0

val riskyTransformWithRetry = Transform[Int, String] {
    n =>
      attempts += 1
      if (attempts < 3) throw new RuntimeException(s"Attempt $attempts failed")
      else s"Success after $attempts attempts"
}.withRetry(maxAttempts = 3, initialDelayMs = 10)

val pipeline = Extract(42) ~> riskyTransformWithRetry
pipeline.unsafeRun(())

Output:

Success after 3 attempts

.onFailure

Catch exceptions and provide fallback values using .onFailure:

import etl4s._

val riskyExtract =
    Extract[Unit, String](_ => throw new RuntimeException("Boom!"))

val safeExtract = riskyExtract.onFailure(e => s"Failed: ${e.getMessage}")
val consoleLoad = Load[String, Unit](println(_))

val pipeline = safeExtract ~> consoleLoad
pipeline.unsafeRun(())

Output:

Failed: Boom!