risp 0.3.0

# Risp [![Build Status](https://travis-ci.org/shybyte/risp.svg?branch=master)](https://travis-ci.org/shybyte/risp) [![codecov](https://codecov.io/gh/shybyte/risp/branch/master/graph/badge.svg)](https://codecov.io/gh/shybyte/risp)

A rusty lisp inspired by Clojure for usage as simple configuration language
 
## Usage in Rust

```rust
  extern crate risp;
  
  use risp::eval_risp_script;
  use risp::types::RispType::Int;
  use risp::core::create_core_environment;
  
  #[test]
  fn test_minimal_example() {
     let mut env = create_core_environment();
     env.set("var", Int(2));
  
     let risp_script = "(+ 40 var)";
     let result = eval_risp_script(risp_script, &mut env);
  
     assert_eq!(result, Ok(Int(42)));
  }
```

## Risp example showing every existing language feature

```clojure
  (def myInt 2)
  
  (def myVector [1 myInt 3])
  
  (def repeated (rep 2 1 2 3))
  
  {:added       (+ myInt 20)
   :multiplied  (* myInt 20)
   :repeated    repeated
   :myVector    myVector
   :myMap       {:key myInt}
   :myString    "Hello"
   :myDoResult  (do
                  (def myInt2 20)
                  (+ myInt myInt2))}
```            


## Convert evaluated Risp to Rust 
```rust
extern crate risp;

use risp::eval_risp_script;
use risp::core::create_core_environment;

struct SimpleSong {
    name: String,
    speed: i64,
    notes: Vec<i64>
}

#[test]
fn test_convert_to_struct_example() {
    let mut env = create_core_environment();

    let risp_script = r#"
    {
        :name "Name"
        :speed 220
        :notes [1 2 3]
    }"#;

    let result = eval_risp_script(risp_script, &mut env).unwrap();

    let simple_song = SimpleSong {
        name: result.get("name").unwrap().unwrap(),
        speed: result.get("speed").unwrap().unwrap(),
        notes: result.get("notes").unwrap().unwrap()
    };

    assert_eq!(simple_song.name, "Name");
    assert_eq!(simple_song.speed, 220);
    assert_eq!(simple_song.notes, vec![1, 2, 3]);
}

```

## Goals
* Simple configuration language
* Subset of Clojure

## Secret Real Goal
* Usable for configuring patches in my pet project [https://github.com/shybyte/rust-midi-patcher](https://github.com/shybyte/rust-midi-patcher) 

## Non-Goals    
* Performance
* Completeness