Module CErrors

This modules implements basic manipulations of errors for use throughout Rocq's code.

Error handling
val push : exn -> Exninfo.iexn
Generic errors.

Anomaly is used for system errors and UserError for the user's ones.

val anomaly : ?loc:Loc.t -> ?info:Exninfo.info -> ?label:string -> Pp.t -> 'a

Raise an anomaly, with an optional location and an optional label identifying the anomaly.

val is_anomaly : exn -> bool

Check whether a given exception is an anomaly. This is mostly provided for compatibility. Please avoid doing specific tricks with anomalies thanks to it. See rather noncritical below.

exception UserError of Pp.t

Main error signaling exception. It carries a header plus a pretty printing doc

val user_err : ?loc:Loc.t -> ?info:Exninfo.info -> Pp.t -> 'a

Main error raising primitive. user_err ?loc pp signals an error pp with optional header and location loc

exception Timeout

register_handler h registers h as a handler. When an expression is printed with print e, it goes through all registered handles (the most recent first) until a handle deals with it.

Handles signal that they don't deal with some exception by returning None. Raising any other exception is forbidden and will result in an anomaly.

Exceptions that are considered anomalies should not be handled by registered handlers.

val register_handler : (exn -> Pp.t option) -> unit
val print : exn -> Pp.t

The standard exception printer

val iprint : Exninfo.iexn -> Pp.t
val print_no_report : exn -> Pp.t

Same as print, except that the "Please report" part of an anomaly isn't printed (used in Ltac debugging).

val iprint_no_report : Exninfo.iexn -> Pp.t
val noncritical : exn -> bool

"Critical" exceptions, such as anomalies or interruptions should not be caught and ignored by mistake by inner Rocq functions by means of doing a "catch-all". They should be handled instead by the compiler layer which is in charge of coordinating the intepretation of Rocq vernaculars.

Please, avoid exceptions catch-all! If you must do so, then use the form:

try my_comp ()
with exn when noncritical exn ->
  my_handler

If you need to re-raise the excepction, you must work to preserve the backtrace and other important information:

try my_comp ()
with exn when noncritical exn ->
  let iexn = Exninfo.capture exn in
  ...
  Exninfo.iraise iexn
val register_additional_error_info : (Exninfo.info -> Pp.t option) -> unit

Register a printer for errors carrying additional information on exceptions. This method is fragile and should be considered deprecated

val to_result : f:('a -> 'b) -> 'a -> ('b, Exninfo.iexn) Stdlib.Result.t

to_result ~f x reifies (non-critical) exceptions into a ('a, iexn) Result.t type