A parametric module that implements the monadic interface for values. The complete documentation can be found in Sugar.S.Promise.
module UserError : S.Params.Errormodule UserMonad : S.Params.Monadtype 'a value = ('a, UserError.t) Result.resultAn alias for Pervasives.result that can only work with errors of your project.
type 'a result = ('a, UserError.t) Result.result UserMonad.tThis type describes a result monad inside a project.
For example, if the concrete module is built on top of Lwt, a value of type unit result will be translated as (unit, error) Pervasives.result Lwt.t.
This combinator is also called bind.
It can be used to chain sequential operations with the current monad. If the computation in the left failed, the operator will propagate the error, skipping the function completely.
Similar to S.Result.bind
val bind_unless : 'a result -> (UserError.t -> 'a result) -> 'a resultSimilar to S.Result.bind_unless
Similar to S.Result.map
val return : 'a -> 'a resultSimilar to S.Result.return
val throw : UserError.t -> 'a resultSimilar to S.Result.throw
module Infix : sig ... endval unwrap : 'a value UserMonad.t -> 'a UserMonad.tUnwraps the successful value as a normal value in the threading monad. If the value is not successful, it will raise an Invalid_arg exception.
val unwrap_or :
(UserError.t -> 'a UserMonad.t) ->
'a value UserMonad.t ->
'a UserMonad.tUnwraps the successful value as a value in the threading monad. Different from unwrap, you can assign an error handler to be executed if the computation failed.
val expect : 'a value UserMonad.t -> string -> 'a UserMonad.tExtracts a successful value from an computation, or raises and Invalid_arg exception with a customized error message.