Execute a block after computing a result.

This crate provides the macro `prog1`, an implementation of the homonymous
Common Lisp macro.

It allows to compute a result, before executing a block that changes values
used to compute the result.

# Examples

```
#[macro_use]
extern crate prog1;

fn main() {
    let mut a = 0;

    assert_eq!(prog1!(a; { a += 1 }), 0);
    assert_eq!(a, 1);
}
```

# Copyright

Copyright 2016 Philipp Matthias Schaefer <philipp.matthias.schaefer@posteo.de>

Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
<LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
option. This file may not be copied, modified, or distributed
except according to those terms.