https://github.com/badboy/small-step-simple-rust

https://fnordig.de/2014/08/12/first-experience-with-rust/
https://github.com/badboy/small-step-simple-rust

Last synced: 9 days ago
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https://fnordig.de/2014/08/12/first-experience-with-rust/

• Host: GitHub
• URL: https://github.com/badboy/small-step-simple-rust
• Owner: badboy
• Created: 2014-08-12T10:33:31.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2015-03-03T19:50:04.000Z (almost 10 years ago)
• Last Synced: 2024-12-24T02:01:36.465Z (12 days ago)
• Language: Rust
• Size: 693 KB
• Stars: 2
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# small-step approach to the SIMPLE language in Rust

[Blog post about my first experience with Rust](https://fnordig.de/2014/08/12/first-experience-with-rust/)

---

This is an implementation of the small-step approach to the SIMPLE language as introduced by

[Tom Stuart](https://twitter.com/tomstuart) in "Understanding Computation", Chapter 1, "The Meaning of Programs".

See his website: .

The usage is pretty simple. As there is no parser for SIMPLE (yet?) you have to write the AST

yourself. A few macros are provided for easy access. You can then create a virtual machine and

pass this AST plus an environment hash. When calling `run`, the machine steps through the code,

reducing it until it reaches a point where no further reduction is possible.

```rust

let mut env = HashMap::new();

env.insert("y".to_string(), number!(1));

let mut m = Machine::new(

    sequence!(

        assign!("x", number!(3)),

        assign!("res", add!(add!(number!(38), variable!("x")), variable!("y")))

        ),

        env

    );

m.run();

// At this point `res` in the HashMap will be `Number(42)`

```

The code is much larger as the equivalent Ruby code. This is both due to the restricitions

of Rust (explicit types and everything, a good thing) and my non-existing experience with Rust

at all (this is my first Rust code larger than a simple "Hello World")

## License

Just like the [original Ruby source code](https://github.com/tomstuart/computationbook), this Rust source code is released under the [CC0 1.0 Public Domain Dedication](http://creativecommons.org/publicdomain/zero/1.0/), which means that you can do whatever you like with it.