baz(foo).expect(format!("Cannot do baz, foo={}", foo)).bar().expect("Cannot do bar");

The best solution I know is error-chain library:

    use errors::ChainErr;
    try!(do_something().chain_err(|| "Something went wrong"));

    [reports.rs:25] ERROR: Cannot write report "Foo" to file "foo.xml".
    [templates.rs:125] ERROR: Cannot process template "header". Check is template file exists and readable.
    [fileio.rs:45] ERROR: Cannot open file "/usr/share/foo/templates/header.tmpl": unable to enter directory "/usr/share/foo". Check directory permissions.

   writing report cannot open file done

Also, you can easily run 10s of thousands of kernel threads (provided you decrease the threads' stack size).

1: http://en.wikipedia.org/wiki/Green_threads

Anyone who has ever consumed an API to build something they don't want to break understands this.

As far as PCI compliance, Braintree.js minimizes your PCI scope as much as tokenization. As long as you serve your site over SSL and maintain adequate security around access to servers, administrative passwords, etc., when using Braintree.js, you'll fall under SAQ A (the lowest possible PCI scope for online merchants).

If you build a webapp in Go, be prepared to spend a lot of time monkeying around with problems that are solved issues on most other platforms.

lis, err := net.Listen("tcp","127.0.0.1:80")

go http.Serve(lis, router)

lis.Close()

  a ^= b
  b ^= a
  a ^= b