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https://github.com/murarth/rusti

REPL for the Rust programming language
https://github.com/murarth/rusti

repl rust

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REPL for the Rust programming language

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# Rusti



A REPL for the Rust programming language.



**The rusti project is deprecated. It is not recommended for regular use.**



## Dependencies



On Unix systems, Rusti requires `libncursesw` (`libncurses` on Mac OS).



## Building



Rusti builds with Rust nightly, using the Cargo build system.  

Currently, it **must** be built using a nightly release of the Rust compiler

released **no later than 2016-08-01**.



The recommended method of installation is to use the following command to

[rustup](https://github.com/rust-lang-nursery/rustup.rs):



    rustup install nightly-2016-08-01



### Installation using Cargo



Rusti can be installed directly using Cargo. The following command will

download, compile, and install Rusti, placing it in `~/.cargo/bin/` or your

operating system equivalent, assuming you haved installed `nightly-2016-08-01`

using `rustup`:



    rustup run nightly-2016-08-01 cargo install --git https://github.com/murarth/rusti



Then you can run it like this:



    rustup run nightly-2016-08-01 ~/.cargo/bin/rusti



### Building from a Git clone



If using [rustup](https://github.com/rust-lang-nursery/rustup.rs),

the following command will create an override to use the correct nightly build

within the `rusti` source tree:



    rustup override add nightly-2016-08-01



Build with Cargo:



    cargo build



Run tests:



    cargo test



Run `rusti`:



    cargo run



Install:



    cargo install



## Usage



Running `rusti` gives a prompt that accepts (most) any valid Rust code.

If the final statement is an expression, the result will be displayed using the

`std::fmt::Debug` trait. This is equivalent to `println!("{:?}", expr);`.



```rust

rusti=> println!("Hello, world!");

Hello, world!

rusti=> 2 + 2

4

rusti=> (0..5).collect::>()

[0, 1, 2, 3, 4]

```



If any delimiters are left open, `rusti` will continue reading input until they are closed.

Only then will the code be executed.



```rust

rusti=> fn factorial(n: u32) -> u32 {

rusti.>     match n {

rusti.>         0 => 0,

rusti.>         1 => 1,

rusti.>         n => n * factorial(n - 1),

rusti.>     }

rusti.> }

rusti=> factorial(3)

6

rusti=> factorial(4)

24

rusti=> factorial(5)

120

```



`rusti` can also run a file given on the command line.  

Note that a `rusti` input file is not quite the same as a typical Rust program.

A typical Rust program contains a function named `main`. While a `rusti`

program can define functions, no functions will be called automatically.

Instead, all statements not within a function body will be executed sequentially,

just like interactive mode.



### Loading Crates



Loading crates which are part of the standard Rust distribution is as easy as

declaring the crate, thusly:



```rust

extern crate foo;

```



However, loading a crate that you have compiled yourself requires some extra steps:



* First, `rusti` must be able to find the location of compiled crate.  

  You can add a path to its search list using the command line option `-L path`.  

  `rusti` accepts any number of `-L` arguments.

* Secondly, `rusti` requires both an `rlib` and a `dylib` version of the

  compiled crate. If you're building your crate with Cargo, the following

  command will build the required files for your project's library:



      cargo rustc --lib -- --crate-type=rlib,dylib



  If you're building with rustc directly, simply add `--crate-type=rlib,dylib`

  to the build command to produce the required files.



### Code completion



`rusti` provides optional support for code completion using [Racer](https://github.com/phildawes/racer).



To enable code completion, install Racer as outlined in the [Installation Instructions](https://github.com/phildawes/racer#installation) and place the `racer` executable into your `PATH`.



## Commands



These are special inputs interpreted by `rusti` that are not directly

evaluated as Rust code, though they may operate on Rust code.



Commands are invoked by entering a line beginning with `.` or `:`, followed by the

name of the command and, perhaps, some text used by the command.



Command names may be arbitrarily abbreviated.  

For example, `.type` may be abbreviated as `.typ`, `.ty`, or `.t`.



### `.block`



The `.block` command will run multiple lines of Rust code as one program.



To end the command and run all code, input `.` on its own line.



```rust

rusti=> .block

rusti+> let a = 1;

rusti+> let b = a * 2;

rusti+> let c = b * 3;

rusti+> c

rusti+> .

6

```



Entering `.q` instead will end the command without running code.



### `.exit`



The `.exit` command exits the REPL loop.



### `.help`



The `.help` command shows usage text for any available commands.



### `.load`



The `.load` command evaluates the contents of a named file.



### `.print`



The `.print` command will display the value of an expression, using the

`std::fmt::Display` trait. This is equivalent to `println!("{}", expr);`.



### `.type`



The `.type` command will display the type of an expression without running it.



```rust

rusti=> .type 42

42 = i32

rusti=> .t 'x'

'x' = char

rusti=> .t "Hello!"

"Hello!" = &'static str

rusti=> .t (1i32, 2u32)

(1i32, 2u32) = (i32, u32)

rusti=> fn foo() -> i32 { 1 }

rusti=> .t foo

foo = fn() -> i32 {foo}

rusti=> .t foo()

foo() = i32

```



## Limitations



Currently, Rusti has the following limitations.

I hope to fix each of them, but some may prove to be large problems to tackle.



* Functions and types are redefined in each round of input.  

  This is inefficient.

* `static` items are also redefined in each round of input.  

  This means that the address of a `static` item will change in every round

  of input and that the values of `mut` items or those with interior mutability

  will be reset to their initial definition on each round of input.  

  This is bad.

* Use of `thread_local!` causes a crash.  

  This is bad.

* `let` declarations are local to the input in which they are defined.  

  They cannot be referenced later and are destroyed after that round of input

  completes its execution.  

  This is inconvenient.

* And more!



## License



Rusti is distributed under the terms of both the MIT license and the

Apache License (Version 2.0).



See LICENSE-APACHE and LICENSE-MIT for details.