Writer

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

handler

writer.handler: collects tell/tellAll output as a list in handler state, starting at []; pair with trampoline.handle.

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

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

tell

tell: append a single value to the writer effect's output log; impure request resuming with null.

tell : w -> Computation null

Append a value to the output log.

tellAll

tellAll: append a list of values to the writer effect's output log in a single impure request; one bind instead of N from mapping tell.

tellAll : [w] -> Computation null

Append a list of values to the output log.