// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. // pretty-expanded FIXME #23616 #![feature(thunk)] use std::thunk::Thunk; pub trait Promisable: Send + Sync {} impl Promisable for T {} pub fn propagate<'a, T, E, F, G>(action: F) -> Thunk<'a, (Result,), Result> where T: Promisable + Clone + 'a, E: Promisable + Clone + 'a, F: FnOnce(&T) -> Result + Send + 'a, G: FnOnce(Result) -> Result + 'a { Box::new(move |result: Result| { match result { Ok(ref t) => action(t), Err(ref e) => Err(e.clone()), } }) } fn main() {}