Error

Error effect with contextual messages and multiple handler strategies.

collecting

Collecting error handler: accumulates errors in state as a list. Resumes computation with null so subsequent effects still execute. Use when you want all errors, not just the first.

State shape: list of { message, context }

raise

Raise an error. Returns a Computation that sends an "error" effect. The handler determines what happens: throw, collect, or recover.

raise : string -> Computation a

raiseWith

Raise an error with context. The context string describes where in the computation the error occurred, enabling stack-trace-like error reports when used with the collecting handler.

raiseWith : string -> string -> Computation a

result

Result error handler: aborts computation with tagged Error value. Uses the non-resumption protocol to discard the continuation.

Returns { _tag = "Error"; message; context; } on error.

strict

Strict error handler: throws on first error via builtins.throw. Use when errors should halt evaluation immediately.

Includes context in the thrown message when available.