An OCaml ppx that helps you write happier code.
let%ok ... = ... in ...
let%some ... = ... in ...
let%await ... = ... in ...
let%await.ok ... = ... in ...
let%await.some ... = ... in ...
match%ok ... with ...
match%some ... with ...
match%await ... with ...
match%await.ok ... with ...
match%await.some ... with ...
if%ok ... then ... else ...
if%some ... then ... else ...
if%await ... then ... else ...
if%await.ok ... then ... else ...
if%await.some ... then ... else ...The main difference between using (let*) and let%await (or the standard
let%lwt) is that, with the ppx version, the async exceptions will correctly
propagate their backtraces.
The following example demonstrates the fully expanded code for %await.ok
let%await.ok p = m in e
(* Is desugared into... *)
let module Reraise = struct
external reraise : exn -> 'a = "%reraise"
end
in
Lwt.backtrace_bind
(fun exn -> try Reraise.reraise exn with exn -> exn)
m
(fun p_result ->
match with
| Ok p -> e
| Error err -> Lwt.return (Error err))