What is JimLang

Jim Lang is a programming language based on JVM with a comprehensive language system, aimed at helping everyone get started in the field of language development.

Usage

add snapshots repository

<repositories>
    <repository>
        <id>jim</id>
        <url>https://oss.sonatype.org/content/repositories/snapshots</url>
    </repository>
</repositories>

set dependency

<dependency>
    <groupId>com.dafei1288</groupId>
    <artifactId>jimlang</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

    @Test
    public void T3() throws IOException{

        String script = """
                function two() { return 2 ; } ;
                function one() { return 1 ; } ;
                var x = one() + two() ;
                println("this message is from jimlang!!!")
                println( x ) ;
                """;

        System.out.println(script);
        System.out.println("--------------------");
        JimLangShell shell = new JimLangShell();
        Object ret = shell.eval(script,null);
    }

or use jsr-223

    @Test
    public void test01() throws ScriptException {
        String script = """
                function two() { return 2 ; } ;
                function one() { return 1 ; } ;
                var x = one() + two() ;
                println("this message is from jimlang!!!")
                println( x ) ;
                """;

        System.out.println(script);
        System.out.println("--------------------");

        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("jim");
        engine.eval(script);
    }

Agent-based Setup (Recommended)

• After cloning, at repo root tell your agent (Codex/Claude Code): "set up dev environment" or "first build and start dev".
• The agent will:
  • verify JDK 21+ and Maven 3.8+;
  • run: mvn -q -DskipTests package;
  • smoke test: bin\jimlang.cmd --eval "println(1+2)" and examples\fibonacci.jim on Windows, or bin/jimlang.sh --eval "println(1+2)" and examples/fibonacci.jim on Unix;
  • start REPL: --cli;
  • optional: build_win.bat (jlink) on Windows; mkos.sh on Linux/WSL.
• See AGENTS.md for details and troubleshooting.

Development

Prerequisites

1. Java >= 21
2. Maven >= 3.8 (If you want to compile and install IoTDB from source code).

Build from source

mvn clean package -DskipTests=true

IDE:

vs-code

Roadmap

• Language: supports early return from nested blocks (if/while/for)
• Build: mvn -q -DskipTests package
• Run a script: bin\\jimlang.cmd examples\\fibonacci.jim
• Start REPL: bin\\jimlang.cmd --cli (or -i)
• Eval one-liner: bin\\jimlang.cmd --eval "println(1+2)" (or -e)
• Read from STDIN: echo println(42) | bin\\jimlang.cmd -
• Enable trace: bin\\jimlang.cmd --trace examples\\fibonacci.jim (or set JIM_TRACE=1)

See also:

• doc/QUICKREF.md language snippets, stdlib, CLI
• doc/ROADMAP.md phases, current status, TODO

Examples

• examples/fibonacci.jim Fibonacci sequence
• examples/stdlib_phase3.jim stdlib showcase
• Scoping demos:
  • examples/scope_func.jim function-local shadowing
  • examples/scope_if.jim block scope shadowing
  • examples/scope_assign_outer.jim assign to outer var inside function

JSON/YAML helpers

var o = { a: 1, b: [2,3] }
var j = json_encode(o)
var x = json_decode(j)
println(json_pretty(o, 2))

// file IO
json_dump(o, "tmp.json", 2)
var ox = json_load("tmp.json")

yml_dump(o, "tmp.yml", 2)
// var oy = yml_load("tmp.yml")  // requires SnakeYAML

Strings

• Triple-quoted multi-line strings: ''' ... ''' (preserves newlines/whitespace). See doc/QUICKREF.md.\n\n## First-class functions

Note: sysfunctions are also first-class values. You can assign and call them:

var p = println
p("ok")

function add(a,b){ return a + b }
var d = add
println( d(2, 3) )

Environment

• Built-ins: env_get(name[, default]) / env_all() / load_env(path[, override=false])
• Behavior:
  • env_get reads from an in-memory overlay (populated via load_env(..., true)) before System.getenv
  • env_all returns merged overlay + process envs (overlay wins)
  • load_env parses .env (supports leading export, # comments, key=value, strip quotes). If file missing, returns {}. See doc/QUICKREF.md.## Web Server (built-in)

function api(req){ return { ok: true } }
start_webserver(8080, "/api/ping", "GET", api)

• Routes: use triples (path, method, handler) or route(path, method, handler) array
• Handler receives req: method, path, params/splat, query, headers, body, json, cookies
• Response helpers: send_text, send_html, send_json, redirect, set_header, response, response_bytes
• Files: send_file, attachment_file; bytes: file_read_bytes

See more: doc/QUICKREF.md (Web section)

• examples/web_app
• examples/env/web_port.jim read .env for PORT and GREETING complete web app (routes, static, cookies, download)

Java Interop via Context (read-only ctx["x"])

• Use JimLangShell.eval(script, sourceName, context) to inject variables:
  • The entire map is exposed as ctx (Map).
  • Identifier-friendly keys ([A-Za-z_][A-Za-z0-9_]*) are also injected as globals (e.g., input, discount).
  • Keys with special characters are accessed by bracket syntax: ctx["user-id"] (currently read-only).

Example (Java):

Map<String,Object> input = Map.of(
  "name", "Alice",
  "scores", Arrays.asList(2,3,5,7)
);
Map<String,Object> ctx = new LinkedHashMap<>();
ctx.put("input", input);
ctx.put("discount", 0.85);
ctx.put("user-id", "u123");
String script = String.join("\n",
  "var sum = 0;",
  "for (var i = 0; i < input.scores.length; i = i + 1) { sum = sum + input.scores[i]; }",
  "var uid = ctx[\"user-id\"];",
  "{ name: input.name, final: sum * discount, uid: uid }"
);
Object ret = new JimLangShell().eval(script, "<inject-demo>", ctx);
System.out.println(ret);

• More examples:
  • examples/DemoEvalInjectCtx.java
  • examples/DemoEvalRoundTrip.java
  • examples/DemoCallFunctionWithParams.java

Note: ctx["x"] is read-only for now; write support (e.g. ctx["k"] = v) can be added later.