DeltaScript

Lightweight scripting language skeleton designed to be easily extended for the specification and implementation of domain-specific languages

Overview

DeltaScript is a concise, statically typed scripting language that is designed to be extended. Its extensions can define new data types, namespaces and functions, but inherit their syntax from DeltaScript. Thus, DeltaScript extensions form a family of syntactically identical domain-specific languages that share an underlying standard library of primitive types and native functions.

Example script

// accepts an input color as a parameter
// returns a list of colors transformed from input in various ways
(~ color input -> color<>) {
    ~ (color -> color) color_functions = [
         ::red, ::green, ::blue, ::greyscale, ::random_color, ::white
    ];
    ~ color<> channels = new color<>;

    for (f in color_functions)
        channels.add(f.call(input));

    return channels;
}

// helper functions that transform a color
greyscale(~ color c -> color) {
    int avg = (c.r + c.g + c.b) / 3;
    return rgba(avg, avg, avg, c.a);
}

// white(), random_color() match signature of other helpers but ignore parameter
// uses the hex code color literal #ffffff - white - RGB[255, 255, 255]
white(~ color c -> color) -> #ffffff
random_color(~ color c -> color) -> rgba(rc(), rc(), rc(), 0xff)
// uses the hexadecimal integer literal 0x100 = 256
rc(-> int) -> rand(0, 0x100)

// isolate a color's RGB channels
red(~ color c -> color) -> rgba(c.r, 0, 0, c.a)
green(~ color c -> color) -> rgba(0, c.g, 0, c.a)
blue(~ color c -> color) -> rgba(0, 0, c.b, c.a)

Development

To-Do

Technologies

ANTLR

The DeltaScript grammar is implemented with ANTLR.

ANTLR is a parser generator tool that uses the rules of a user-defined grammar to generate code in a given target language to easily lex and parse program files that are supposed to conform with the rules of the input grammar.

Java

The official implementation of DeltaScript is an interpreter that targets Java 17.

Use Cases

More information