package capnp-rpc-lwt

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Functions for service implementors.

type ('a, 'b) method_t = 'a -> (unit -> unit) -> 'b StructRef.t

An ('a, 'b) method_t is a method implementation that takes a reader for the parameters and a function to release the capabilities in the parameters, and returns a promise for the results.

module Response : sig ... end
val return : 'a Response.t -> 'a StructRef.t

return r wraps up a simple local result as a promise.

val return_empty : unit -> 'a StructRef.t

return_empty () is a promise for a response with no payload.

val return_lwt : (unit -> ('a Response.t, [< `Capnp of Capnp_rpc.Error.t ]) Lwt_result.t) -> 'a StructRef.t

return_lwt fn is a local promise for the result of Lwt thread fn (). If fn () fails, the error is logged and an "Internal error" returned to the caller. If it returns an Error value then that error is returned to the caller. Note that this does not support pipelining (any messages sent to the response will be queued locally until it fn has produced a result), so it may be better to return immediately a result containing a promise in some cases.

val fail : ?ty:Capnp_rpc.Exception.ty -> ('a, Stdlib.Format.formatter, unit, 'b StructRef.t) Stdlib.format4 -> 'a

fail msg is an exception with reason msg.

val fail_lwt : ?ty:Capnp_rpc.Exception.ty -> ('a, Stdlib.Format.formatter, unit, (_, [> `Capnp of Capnp_rpc.Error.t ]) Lwt_result.t) Stdlib.format4 -> 'a

fail_lwt msg is like fail msg, but can be used with return_lwt.


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