Lice

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Travis CI
AppVeyor
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About

This is the interpreter of Lice language, a dialect of Lisp, run on JVM platform.

It supports call-by-value, call-by-name, call-by-need(we sometimes call it lazy evaluation) at the same time. Functions and values are treated as the same. Dynamic scoping, because I can't find a better scoping solution for a interpreted language.

• About the Language
• A simple Haskell implementation
• (Feature!) IntelliJ IDEA Plugin

See FeatureTest to learn more about the language's features.

Also, as the main repo for the Lice language, this repo will not be updated very frequently.
Instead, I do language feature experiments in The tiny version of Lice, which is more actively updated and not guarenteed be backward capable.
Once a feature is finished and tested, and not considered harmful, I'll copy the codes here and publish releases.

It looks like

; print a string
(print "Hello " "World" "\n")

; travel through a range
(for-each i (.. 1 10) (print i "\n"))

; define a call-by-name function
(defexpr fold ls init op
 (for-each index-var ls
   (-> init (op init index-var))))

; invoke the function defined above
(fold (.. 1 4) 0 +)

; passing a call-by-value lambda to a call-by-value lambda
((lambda op (op 3 4)) (lambda a b (+ (* a a) (* b b))))

; to define a call-by-need lambda, use `lazy`.

Building

To use Lice with build tools, first add jcenter to your repositories list.

With gradle, add this to your dependencies list:

compile 'org.lice:lice:3.3.2'

Or with maven:

<dependency>
  <groupId>org.lice</groupId>
  <artifactId>lice</artifactId>
  <version>3.3.2</version>
  <type>pom</type>
</dependency>

Or with ivy:

<dependency org='org.lice' name='lice' rev='3.3.2'>
  <artifact name='lice' ext='pom'/>
</dependency>

Alternatively, you can download the nightly jar for the newest commit on AppVeyor.

Script API

import javax.script.*;

public class LiceScriptEngineTest {
    public static void main() throws Exception {
        ScriptEngine engine = new ScriptEngineManager().getEngineByName("lice");
        engine.eval("(-> x 10)");
        engine.eval("(print x)");
    }
}

Lice performance

Code to run:

; loops
(def loop count block (|>
    (-> i 0)
    (while (< i count) (|> (block i)
    (-> i (+ i 1))))))

; invoking the function
(loop 200000 (lambda i (|>
    (defexpr let x y block (|>
        (-> x y) ; this is actually an issue of lice.
        (block)
        (undef x)))
    (let reimu 100 (lambda (|> x))))))

(print "loop count: " i)

Environment: Ubuntu Linux 16.04, HotSpot 1.8u151, Intel core i7 4720HQ 2.6 GHz

Lice invoking Java

Lice has handy APIs for interacting with Java.

; declare an extern function
; must be a static Java function
(extern "java.util.Objects" "equals")

; calling the extern function
(equals 1 1)

Java invoking Lice

This project provides handy APIs for running Lice codes from Java.

class SomeClass {
  public static void main(String[] args){
    // Running Lice
    System.out.println(Lice.run("(+ 1 1)")); // prints 2
    System.out.println(Lice.run(new File("example.lice"))); // run codes in a file
    
    // Lice API
    SymbolList env = new SymbolList();
    Lice.run("(def blablabla a (+ a a)) (-> myVar 233)", env);
    env.extractLiceFunction("blablabla").invoke(233); // result: 466
    int var = ((Number) env.extractLiceVariable("myVar")).intValue(); // result: 233
  }
}