Writer

Append-only output effect: tell/tellAll with list-collecting handler.

handler

Standard writer handler. Collects tell output in state as a list. Initial state: []

handle { handlers = writer.handler; state = []; } comp

tell

Append a value to the output log.

tell : w -> Computation null

tellAll

Append a list of values to the output log.

tellAll : [w] -> Computation null