Conditions

CL-style condition system: signal/warn with restart-based recovery.

collectConditions

Collecting handler: accumulates conditions in state, resumes with continue. State shape: list of { name, data } Initial state: []

fail

Fail handler: throws on any condition. Ignores available restarts. Use as a last-resort handler.

ignore

Ignore handler: resumes with null for any condition. All conditions are silently discarded.

signal

Signal a condition. The handler chooses a restart strategy.

signal : string -> any -> [string] -> Computation any

Arguments: - name — condition name (e.g. "division-by-zero", "file-not-found") - data — condition data (error details, context) - restarts — list of available restart names

The handler receives { name, data, restarts } and returns a { restart, value } attrset. The continuation receives this choice.

warn

Signal a warning condition. Like signal but with a conventional "muffle-warning" restart. If the handler doesn't muffle, the computation continues normally.

warn : string -> any -> Computation null

withRestart

Create a handler that invokes a specific restart for a named condition. For all other conditions, falls through (throws).

withRestart : string -> string -> any -> handler

Arguments: - condName — condition name to match - restartName — restart to invoke - restartVal — value to pass via the restart