Error Channel Operations

ZIO's error channel supports a rich set of transformations beyond simple recovery. These operators let us reshape, inspect, and restructure errors and successes without necessarily resolving the failure — useful when threading error values through a larger computation.

• Map Operations — transform error values with mapError, mapErrorCause, and mapAttempt without recovering from the failure.
• Chaining Effects Based on Errors — sequence a second effect that depends on the first effect's typed error using flatMapError.
• Filtering the Success Channel — convert success values that fail a predicate into typed errors using filterOrFail, filterOrDie, and filterOrElse.
• Tapping Errors — inspect failure values, defects, and Cause graphs as a side effect without altering the error channel, using tapError, tapErrorCause, and tapDefect.
• Exposing Errors in the Success Channel — move typed failures into the success channel as Either values using ZIO#either, then submerge them back with ZIO#absolve.
• Exposing the Cause in the Success Channel — surface the full Cause[E] graph in the success channel using ZIO#cause, then submerge it with ZIO#uncause.
• Converting Defects to Failures — turn defects back into typed failures using absorb and resurrect.
• Error Refinement — narrow or widen the typed error channel using refineOrDie, refineToOrDie, unrefine, and unrefineTo.
• Flattening Optional Error Types — collapse Option[E] error types into plain E using ZIO#flattenErrorOption, providing a default error for the None case.
• Merging the Error Channel into the Success Channel — collapse the error channel into the success channel using ZIO#merge when both types are compatible, producing an infallible effect.
• Flipping Error and Success Channels — swap the error and success channels using flip and flipWith to apply success-channel operators to errors.
• Rejecting Some Success Values — convert select success values into typed failures using ZIO#reject and ZIO#rejectZIO with a partial function.
• Zooming In on Nested Values — navigate Option and Either values nested inside ZIO effects using some, unsome, left, right, and related operators.