Status

The execution status produced by a Stage.

A Status travels alongside the output (or absence of output) in a Yield and is accumulated as stages are composed. There are two possible states:

• Status.Success — the stage completed normally and processing may continue.
• Status.Complete — a unit of work has finished. Passed to Evolution when selecting the next continuation stage; the enclosing cycle operators (Loop, Repeat and the rest of h8io.stages.cycles in the lib module) use it to end the current cycle. When errors is empty this represents clean completion; when errors is non-empty it carries one or more accumulated errors.

Statuses form a monoid under combine, used when merging the results of composed stages: Success is the identity element and Complete accumulates errors on combination.