Source file monad.ml

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module Make (Trace : Traced_sigs.Trace.S) :
  Traced_sigs.Monad.S with type 'error trace = 'error Trace.trace = struct
  include Bare_structs.Monad

  type 'error trace = 'error Trace.trace

  let error_trace e = error (Trace.make e)

  let fail_trace e = fail (Trace.make e)

  let rec join_e_errors trace_acc = function
    | Ok _ :: ts -> join_e_errors trace_acc ts
    | Error trace :: ts -> join_e_errors (Trace.conp trace_acc trace) ts
    | [] -> Error trace_acc

  let rec join_e = function
    | [] -> unit_e
    | Ok () :: ts -> join_e ts
    | Error trace :: ts -> join_e_errors trace ts

  let all_e ts =
    let rec aux acc = function
      | [] -> Ok (Stdlib.List.rev acc)
      | Ok v :: ts -> aux (v :: acc) ts
      | Error trace :: ts -> join_e_errors trace ts
    in
    aux [] ts

  let both_e a b =
    match (a, b) with
    | (Ok a, Ok b) -> Ok (a, b)
    | (Error err, Ok _) | (Ok _, Error err) -> Error err
    | (Error erra, Error errb) -> Error (Trace.conp erra errb)

  let join_ep ts = all_p ts >|= join_e

  let all_ep ts = all_p ts >|= all_e

  let both_ep a b = both_p a b >|= fun (a, b) -> both_e a b
end