trace -package:streamly package:fused-effects

Append a message to the trace log.

An effect that provides a record of String values ("traces") aggregate during the execution of a given computation. Predefined carriers:

• Control.Carrier.Trace.Printing, which logs to stderr in a MonadIO context.
• Control.Carrier.Trace.Returning, which aggregates all traces in a @[String].
• Control.Carrier.Trace.Ignoring, which discards all traced values.

Run a Trace effect, ignoring all traces.

runTrace (trace s) = pure ()

runTrace (pure a) = pure a

Run a Trace effect, printing traces to stderr.

runTrace (trace s) = liftIO (putStrLn s)

runTrace (pure a) = pure a

Run a Trace effect, returning all traces as a list.

runTrace (pure a) = pure ([], a)

runTrace (trace s) = pure ([s], ())