The trace type (included as part of the Tezos_lwt_result_stdlib.Lwtreslib.TRACE module is abstract in this interface but it is made concrete in the instantiated error monad (see error_monad.mli).
The idea of abstracting the trace is so that it can evolve more easily. Eventually, we can make the trace abstract in the instantiated error monad, we can have different notions of traces for the protocol and the shell, etc.
val pp_print :
(Stdlib.Format.formatter -> 'err -> unit) ->
Stdlib.Format.formatter ->
'err trace ->
unitpp_print pretty-prints a trace of errors
val pp_print_top :
(Stdlib.Format.formatter -> 'err -> unit) ->
Stdlib.Format.formatter ->
'err trace ->
unitpp_print_top pretty-prints the top errors of the trace
val encoding : 'error Data_encoding.t -> 'error trace Data_encoding.tval fold : ('a -> 'error -> 'a) -> 'a -> 'error trace -> 'afold f init trace traverses the trace (in an unspecified manner) so that init is folded over each of the error within trace by f. Typical use is to find the worst error, to check for the presence of a given error, etc.