Eager_deferred.ResultSourceinclude Core.Monad.S2
with type ('a, 'b) t = ('a, 'b) Core.Result.t Async_kernel.Deferred.tSame as Infix, except the monad type has two arguments. The second is always just passed through.
e.g., failf "Couldn't find bloogle %s" (Bloogle.to_string b).