# dst

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Dst is a functional and imperative programming language and bytecode interpreter. The syntax
resembles lisp (and the language does inherit a lot from lisp), but lists are replaced
by other data structures with better utility and performance (arrays, tables, structs, tuples).
The language can also easily bridge to native code, and supports abstract datatypes
for interfacing with C. Also support meta programming with macros. 
The bytecode vm is a register based vm loosely inspired by the LuaJIT bytecode format. 

There is a repl for trying out the language, as well as the ability
to run script files. This client program is separate from the core runtime, so
dst could be embedded into other programs.

Implemented in mostly standard C99, dst runs on Windows, Linux and macOS.
The few features that are not standard C (dynamic library loading, compiler specific optimizations),
are fairly straight forward. Dst can be easily ported to new platforms.

There is not much in the way of documentation yet because it is still a "personal project" and
I don't want to freeze features prematurely. You can look in the examples directory, the test directory,
or the file `src/compiler/boot.dst` to get a sense of what dst code looks like.

## Features

* First class closures
* Garbage collection
* First class green threads (continuations)
* Mutable and immutable arrays (array/tuple)
* Mutable and immutable hashtables (table/struct)
* Mutable and immutable strings (buffer/string)
* Lisp Macros
* Byte code interpreter with an assembly interface, as well as bytecode verification
* Proper tail calls.
* Direct interop with C via abstract types and C functions
* Dynamically load C libraries
* Lexical scoping
* Imperative Programming as well as functional
* REPL

## Usage

A repl is launched when the binary is invoked with no arguments. Pass the -h flag
to display the usage information.

```
$ ./dst
Dst 0.0.0 alpha  Copyright (C) 2017-2018 Calvin Rose
> (+ 1 2 3)
6
> (print "Hello, World!")
Hello, World!
nil
> (exit)
$ ./dst -h
usage: ./dst [options] scripts...
Options are:
-h Show this help
-v Print the version string
-r Enter the repl after running all scripts
$
```

## Docmentation

API documentation and design documents will be added to the `doc` folder as they are written.
As of March 2018, specifications are sparse because dst is evolving.

## Compiling and Running

Dst can be built with Make or CMake.
Use Make if you are on a posix system and don't like CMake.
Use CMake if you are on Windows or like CMake.

### Make

```sh
cd somewhere/my/projects/dst
make
make test
```

### CMake

On a posix system using make as the backend, compiling and running is as follows (this is the same as 
most CMake based projects).

```sh
cd somewhere/my/projects/dst
mkdir -p build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make
make test
```

The repl can also be run with the CMake run target.
```sh
make run
```

## Examples

See the examples directory for some example dst code.

## Editor

There is some preliminary vim syntax highlighting in [dst.vim](https://github.com/bakpakin/dst.vim).
Generic lisp synatx highlighting should provide good results, however.