Examples and recipes

These assume a Mini-like config: let, fn, if, while, for, ;, { }, "strings", // comments. Adjust keywords to the language you generated.

Embed + run

#include <ReScripted.h>
#include "mylang.hpp" // from embed_language.sh

int main() {
  rescripted::Engine engine;
  engine.add_language(rescripted::Language::compile(rescripted::embed::mylang));
  engine.bind("print", [](const std::vector<rescripted::Value>& args) {
    for (const auto& a : args) std::cout << a.to_string() << '\n';
    return rescripted::Value();
  });
  auto id = engine.load_file("scripts/hello.mylang");
  engine.run(id);
  engine.unload(id);
}

Script: functions and math

let x = 2 + 3 * 4;
fn double(n) { return n * 2; }
fn answer() { return double(x); }

After run, engine.get("x") is 14, engine.call("answer") is 28.

Script: host command + type + decorator

@export
command ping() {
  return "pong";
}

entity Hero {
  hp = 10;
  name = "Ada";
}

Requires custom.function_kinds (command), custom.types (entity), custom.decorators (export).

Script: control flow

let n = 0;
while n < 3 {
  n = n + 1;
}
if n == 3 {
  print("ok");
} else {
  print("bad");
}
for i 5 {
  print(i);
}
for item [1, 2, 3] {
  print(item);
}

for i 5 iterates 0..4. for item [1,2,3] iterates values.

Imports: C++ package, installed script, dotted file

JSON: imports.enabled, keywords (import or #banana), module_separator ".", bind_as "namespace".

add_executable(game src/main.cpp stdlib/math.c++)

engine.add_library("math", rescripted::library::math);
engine.add_library_file("Workshop", "packages/Workshop/main.mylang");
engine.add_search_path("packages");

import math
import company.app.library
import Workshop
let x = math.sqrt(9)
let n = library.times(3)

company.app.library loads company/app/library.mylang next to the importer (or on a search path). # keywords cannot also be line comments.

Hot reload

engine.unload("scripts/ai.mylang");
auto id = engine.load_file("scripts/ai.mylang");
engine.run(id);

One-shot

auto v = engine.eval("1 + 2;", "MyLang");

Inspect a compiled config

auto lang = rescripted::Language::compile(json);
auto keywords = lang.definition()["keywords"]["reserved"];

Mini demo in this repo

examples/mini/ — mini.json embedded into mini_host, hello.mini loaded at runtime. Copy the pattern, not the files into the user’s language folder unless they asked for Mini itself.