Liyad

Let's make your yet another DSL with Lisp S-expression!

Liyad (Lisp yet another DSL interpreter, or LIYAD is yum and delicious) is very small Lisp interpreter written in JavaScript.
You can easily start making your new DSL using Lisp and S-expression.

Install

from NPM:

$ npm install liyad --save

or download UMD from release page.

NOTICE:
Use with webpack >= 5

If you get the error:

Module not found: Error: Can't resolve '(importing/path/to/filename)'
in '(path/to/node_modules/path/to/dirname)'
Did you mean '(filename).js'?`

Add following setting to your webpack.config.js.

{
    test: /\.m?js/,
    resolve: {
        fullySpecified: false,
    },
},

On webpack >= 5, the extension in the request is mandatory for it to be fully specified if the origin is a '.mjs' file or a '.js' file where the package.json contains '"type": "module"'.

Install CLI

See liyad-cli .

$ npm install -g liyad-cli
$ liyad

Playground

https://shellyln.github.io/liyad/playground.html

---

Features

• APIs to customize all operators and macros
• Builtin S-expression parser
• Builtin minimal Lisp interpreter
• Reference implementation of LSX (alternative JSX notation using Lisp)

---

Real world examples

• Ménneu
  Component-based extensible document processor
• mdne - Markdown Neo Edit
  A simple markdown and code editor powered by Markdown-it, Ace and Carlo.
• Tynder
  TypeScript friendly Data validator for JavaScript.

---

What is LSX

LSX is an alternative JSX notation using Lisp.

LSX and Liyad advantages:

• No transpiler needed

  • Liyad uses ES6 template literal syntax.
    You don't pass the entire code to transpile and evaluate it.
    Save your coding times.

• Secure execution for untrusted contents

  • No host environment's symbols are accessible from evaluated user contents by default.
    Malicious codes can not make a serious attack.

• Simple and powerful

  • What you can do with JSX can be done with LSX.
    Plus, LSX itself is a complete data description format and is a complete programming language,
    so you can write more concise and powerful.

The LSX runtime directly calls React.createElement (or a JSX Factory function such as RedAgate, Vue.js, etc.) as a Lisp function,
Convert a Lisp list to a renderer component object tree.

In order to resolve the renderer component, you must register the object's constructor with the LSX runtime in advance.

All unresolved lisp function symbols are dispatched to React.createElement('some_unresolved_name', ...).
You can declare HTML/XML standard tags.

As with JSX, LSX must always return a single component.
Using Template Lisp function instead of JSX Fragment tag will produce the same result.

Example:

lsx`
(Template
    (select (@ (style (display "inline-block")
                      (width "300px") )
               (className "foo bar baz")
               (onChange ${(e) => this.handleExampleSelected(e.target.value)}) )
        ($=for ${exampleCodes}
            ($=if (== (% $index 2) 1)
                (option (@ (value $index)) ($concat "odd: " ($get $data "name"))) )
            ($=if (== (% $index 2) 0)
                (option (@ (value $index)) ($concat "even: " ($get $data "name"))) ))))`;

See also:

Playground's source code is written in LSX.

---

Usage

Output S-expression into JSON:

import { S } from 'liyad';

console.log(
    JSON.stringify(S`
        ($list
            1 2 3 "a" "b" "C"
            ($list 4 5 6) ${"X"} ${["Y", "Z"]} )`

        // You can also parse by calling w/o template literal syntax as following:
        // S(' ... ')
    )
);

Output:

[{"symbol":"$list"},1,2,3,"a","b","C",[{"symbol":"$list"},4,5,6],{"value":"X"},{"value":["Y","Z"]}]

Run minimal Lisp interpreter:

import { lisp } from 'liyad';

console.log(
    JSON.stringify(lisp`
        ($defun fac (n)
            ($if (== n 0)
                1
                (* n ($self (- n 1))) ))
        ($list
            1 2 (fac 3) "a" "b" "c"
            ($list 4 5 (fac 6) ${"X"} ${["Y", "Z"]}) )`

        // You can also evaluate by calling w/o template literal syntax as following:
        // lisp(' ... ')
    )
);

Output:

[1,2,6,"a","b","c",[4,5,720,"X",["Y","Z"]]]

Render web page with LSX:

import * as React    from 'react';
import * as ReactDOM from 'react-dom';
import { LSX }       from 'liyad';

var lsx = null;

const exampleCodes = [{
    name: "Example1: factorial",
    code: ` ... `
}, {
    name: "Example2: Hello, World!",
    code: ` ... `,
}];

class ExampleLoader extends React.Component {
    constructor(props, context) {
        super(props, context);
        this.state = {};
    }

    handleExampleSelected(i) {
        this.props.loadExample(i);
    }

    render() {
        return (lsx`
        (Template
            (select (@ (style (display "inline-block")
                              (width "300px") )
                       (onChange ${(e) => this.handleExampleSelected(e.target.value)}) )
                ($=for ${exampleCodes}
                    (option (@ (value $index)) ($get $data "name")) )))`);
    }
}

class App extends React.Component {
    constructor(props, context) {
        super(props, context);
        this.state = {};
    }

    loadExample(i) {
        console.log(exampleCodes[i].code);
    }

    render() {
        return (lsx`
        (Template
            (div (@ (style (margin "4px")))
                (ExampleLoader  (@ (loadExample ${(i) => this.loadExample(i)}))) ))`);
    }
}

var lsx = LSX({
    jsx: React.createElement,
    jsxFlagment: React.Fragment,
    components: {
        ExampleLoader,
        App,
    },
});

ReactDOM.render(lsx`(App)`, document.getElementById('app'));

Build your new DSL:

import { SxFuncInfo,
         SxMacroInfo,
         SxSymbolInfo,
         SExpression,
         SxParserConfig,
         defaultConfig,
         installCore,
         installArithmetic,
         installSequence } from 'liyad';

const myOperators: SxFuncInfo[] = [{
    name: '$__defun',
    fn: (state: SxParserState, name: string) => (...args: any[]) => {
        // S expression: ($__defun 'name '(sym1 ... symN) 'expr ... 'expr)
        //  -> S expr  : fn
        const car: SxSymbol = $$first(...args);
        if (args.length < 3) {
            throw new Error(`[SX] $__defun: Invalid argument length: expected: ${3} / args: ${args.length}.`);
        }
        const fn = $__lambda(state, name)(...args.slice(1));
        state.funcMap.set(car.symbol, {
            name: car.symbol,
            fn: (st, nm) => fn
        });
        return fn;
    },
}];

const myMacros: SxMacroInfo[] = [{
    name: '$defun',
    fn: (state: SxParserState, name: string) => (list) => {
        // S expression: ($defun name (sym1 ... symN) expr ... expr)
        //  -> S expr  : ($__defun 'name '(sym1 ... symN) 'expr ... 'expr)
        return [{symbol: '$__defun'},
            ...(list.slice(1).map(x => quote(state, x))),
        ];
    },
}];

const mySymbols: SxSymbolInfo[] = [
    {name: '#t', fn: (state: SxParserState, name: string) => true}
];

export const MyDSL = (() => {
    let config: SxParserConfig = Object.assign({}, defaultConfig);

    config = installCore(config);
    config = installArithmetic(config);
    config = installSequence(config);

    config.stripComments = true;

    config.funcs = (config.funcs || []).concat(myOperators);
    config.macros = (config.macros || []).concat(myMacros);
    config.symbols = (config.symbols || []).concat(mySymbols);

    return SExpression(config);
})();


console.log(
    JSON.stringify(MyDSL`( ... )`)
);

---

Extended syntax

---

Comments

# This is a line comment

(# ; <-- This is a object literal, not a line comment
)

; This is a line comment

#|
This is a block comment
 |#

---

Here document:

lisp preset interpreter:

"""
Hello, Liyad!
"""

is equivalent to:

($concat
"
Hello, Liyad!
"
)

LSX preset interpreter:

"""
Hello, Liyad!
"""

is equivalent to:

(Template
"
Hello, Liyad!
"
)

Template on the LSX preset interpreter, it is mapped to the function passed by LsxConfig.JsxFragment.
See also: Fragments (React), Template (RedAgate).

---

Here document with variable substitution:

"""
Hello, %%%($get name)!
"""

is equivalent to:

(Template
"
Hello, " ($get name) "!
"
)

---

Here document with custom function:

"""div
Hello, %%%($get name)!
"""

is equivalent to:

(div
"
Hello, " ($get name) "!
"
)

Here document with custom function and LSX props:

"""div@{(id "123") (class "foo bar baz")}
Hello, %%%($get name)!
"""

is equivalent to:

(div (@ (id "123") (class "foo bar baz"))
"
Hello, " ($get name) "!
"
)

---

Spread operator

($list 1 2 ...($concat (3 4) (5 6)) 7 8)

is equivalent to:

($list 1 2 ($spread ($concat (3 4) (5 6))) 7 8)

and is to be:

[1,2,3,4,5,6,7,8]

$spread is NOT a macro. The list passed as a parameter is spliced ​​after evaluation.

---

Splice macro

($list 1 2 3 4 ($splice (5 6 7 8)) 9 10)

is equivalent to:

($list 1 2 3 4 5 6 7 8 9 10)

(($splice ($call x add)) 5 7)

is equivalent to:

($call x add 5 7)

---

Shorthands

$set

(::foo:bar:baz= 7)

is equivalent to:

($set ("foo" "bar" "baz") 7)

$get

($list ::foo:bar:baz)

is equivalent to:

($list ($get "foo" "bar" "baz"))

$call

(::foo:bar@baz 3 5 7)

is equivalent to:

($call ($get "foo" "bar") baz 3 5 7)

---

Rest parameter

($defun f (x ...y)
    ($list x y) )

($list
    (f 1)
    (f 1 2)
    (f 1 2 3)
    (f 1 2 3 4)
    (f 1 2 3 4 5) )

is to be:

[
    [1,[]],
    [1,[2]],
    [1,[2,3]],
    [1,[2,3,4]],
    [1,[2,3,4,5]]
]

---

Verbatim string literal

Verbatim string literal

($last @"c:\documents\files\u0066.txt")

is to be:

"c:\\documents\\files\\u0066.txt"

Normal string literal

($last "c:\documents\files\u0066.txt")

is to be:

"c:documents\filesf.txt"

---

Object literal

(# (foo "a")
   (bar 10)
   (baz) )

is to be:

{
    "foo": "a",
    "bar": 10,
    "baz": true
}

---

nil, null, undefined

($list nil null undefined)

is to be:

[[], null, undefined]

See this.

---

Refer the function

($defun fn(x) (+ x 1))
($let x (<- fn))
(x 3) ;; 4

Liyad is Lisp-2 language.

---

Lambda and closure

Lambda

($let fn (-> (x y z) (+ x y z)))

(fn 1 2 3) ;; 6

$lambda is synonym of ->.

Closure

($let fn ($local ((a 1)(b 2)(c 3))
    (|-> (x y z) use (a b c)
        ($set a (+ a x))
        ($set b (+ b y))
        ($set c (+ c z))
        (+ a b c) )))

(fn 1 2 3) ;; 12
(fn 1 2 3) ;; 18

$closure is synonym of |->.

is equivalent to:

($let fn ($local ((a 1)(b 2)(c 3))
    ($capture (a b c) (-> (x y z)
        ($set a (+ a x))
        ($set b (+ b y))
        ($set c (+ c z))
        (+ a b c) ))))

(fn 1 2 3) ;; 12
(fn 1 2 3) ;; 18

$capture can also be used with $defun.

---

Recursive call

($defun tarai(x y z)
    ($if (<= x y)
        y
        ($self ($self (- x 1) y z)
               ($self (- y 1) z x)
               ($self (- z 1) x y) )))

$self refers to the function currently defined by $defun or ->.

---

Macro

($defmacro FOR (!i <[> <FROM> s <TO> e <]> ...body)
    `($last
        ($local ((,i ,s))
            ($while (<= ,i ,e)
                ,@body
                ($set ,i (+ ,i 1)) ))))

($let c1   0)
($let c2 100)
(FOR p [ FROM (+ 1) TO (+ 6 -3) ]
    ($set c1 (+ c1 p))
    ($set c2 (+ c2 p)) )

Parameter type checking

formal parameter	constraint
!token	parameter should be symbol
<token>	parameter should be symbol named token
token:number	parameter should be number
token:string	parameter should be string
token:function	parameter should be function
token:list	parameter should be list
token:symbol	parameter should be symbol

Don't put spaces between ! < > :type and token.

Type checking checks formal parameter types before evaluation.

Macro can be overloaded with the same macro name but different numbers of formal parameters.

---

This object

($let fn (-> () $this))
($let xx (# (a 3)
            (b 5)
            (f fn) ))
($json-stringify (::xx@f)) ;; {"a":3,"b":5}

---

Compiling functions and lambdas (experimental)

interpreting	compiling
$defun	$$defun	define the function
$lambda	$$lambda	define the lambda
->	=>	define the lambda
$closure	$$closure	define the closure
|->	|=>	define the closure

---

APIs

SExpression / SExpressionAsync

Create a new DSL.

interface SxParserConfig {
    raiseOnUnresolvedSymbol: boolean;
    enableEvaluate: boolean;
    enableHereDoc: boolean;
    enableSpread: boolean;
    enableSplice: boolean;
    enableShorthands: boolean;
    enableVerbatimStringLiteral: boolean;
    enableTailCallOptimization: boolean;
    enableRegExpMatchOperator: true,     // IMPORTANT: Turn off to prevent ReDoS when executing untrusted code
    enableCompilationOperators: boolean; // IMPORTANT: Turn off to prevent DoS when executing untrusted code
    stripComments: boolean;
    wrapExternalValue: boolean;
    reservedNames: SxReservedNames;
    returnMultipleRoot: boolean;
    maxEvalCount: number;                // IMPORTANT: Set positive value to prevent DoS when executing untrusted code

    jsx?: (comp: any, props: any, ...children: any[]) => any;
    JsxFragment?: any;

    funcs: SxFuncInfo[];
    macros: SxMacroInfo[];
    symbols: SxSymbolInfo[];

    funcSymbolResolverFallback?: SxFunc;
    valueSymbolResolverFallback?: SxSymbolResolver;
}

function SExpression(config: SxParserConfig): (strings: TemplateStringsArray | string, ...values?: any[]) => SxToken

• returns : Template literal function.
• config : Parser config.

---

S

Parse a S-expression.

function S(strings: TemplateStringsArray | string, ...values?: any[]): SxToken

• returns : S-expression parsing result as JSON object.
• strings : Template strings.
• values : values.

---

lisp

Evaluate a Lisp code.

function lisp(strings: TemplateStringsArray | string, ...values?: any[]): SxToken

• returns : Evalueting result value of Lisp code.
  • If input Lisp code has multiple top level parenthesis,
    result value is last one.
• strings : Template strings.
• values : values.

---

lisp_async

Evaluate a Lisp code.
(asynchronous features are enabled.)

function lisp_async(strings: TemplateStringsArray | string, ...values?: any[]): Promise<SxToken>

• returns : Promise that evalueting result value of Lisp code.
  • If input Lisp code has multiple top level parenthesis,
    result value is last one.
• strings : Template strings.
• values : values.

---

LM

Evaluate a Lisp code (returns multiple value).

function LM(strings: TemplateStringsArray | string, ...values?: any[]): SxToken

• returns : Evalueting result value of lisp code.
  • If input Lisp code has multiple top level parenthesis,
    result value is array.
• strings : Template strings.
• values : values.

---

LM_async

Evaluate a Lisp code (returns multiple value).
(asynchronous features are enabled.)

function LM_async(strings: TemplateStringsArray | string, ...values?: any[]): Promise<SxToken>

• returns : Promise that evalueting result value of lisp code.
  • If input Lisp code has multiple top level parenthesis,
    result value is array.
• strings : Template strings.
• values : values.

---

LSX

Evaluate a Lisp code as LSX.

interface LsxConfig {
    jsx: (comp: any, props: any, ...children: any[]) => any;
    jsxFlagment: any;
    components: object;
}

function LSX<R = SxToken>(lsxConf: LsxConfig): (strings: TemplateStringsArray, ...values: any[]) => R

• returns : Template literal function.
• lsxConf : LSX config.

---

LSX_async

Evaluate a Lisp code as LSX.
(asynchronous features are enabled.)

interface LsxConfig {
    jsx: (comp: any, props: any, ...children: any[]) => any;
    jsxFlagment: any;
    components: object;
}

function LSX_async<R = SxToken>(lsxConf: LsxConfig): (strings: TemplateStringsArray, ...values: any[]) => Promise<R>

• returns : Template literal function.
• lsxConf : LSX config.

(lisp | lisp_async | LM | LM_async : SExpressionTemplateFn) methods

evaluateAST

evaluateAST(ast: SxToken[]): SxToken;

• returns : evaluation result value.
• ast : AST to evaluate. it should be enclosed in [].

  lisp.evaluateAST([[{symbol: '+'}, 1, 2 ,3]]);  // 6

repl

repl(): SExpressionTemplateFn;

• returns : Template literal function that will keep variables and states for each evaluation.

setGlobals

setGlobals(globals: object): SExpressionTemplateFn;

• returns : myself (template literal function).
• globals : Global variables to preset.

appendGlobals

appendGlobals(globals: object): SExpressionTemplateFn;

• returns : myself (template literal function).
• globals : Global variables to preset.

setStartup

setStartup(strings: TemplateStringsArray | string, ...values: any[]): SExpressionTemplateFn;

• returns : myself (template literal function).
• strings : Startup code that evaluate before each evaluation of user code.

setStartupAST

setStartupAST(ast: SxToken[]): SExpressionTemplateFn;

• returns : myself (template literal function).
• ast : Startup code AST that evaluate before each evaluation of user code.

appendStartup

appendStartup(strings: TemplateStringsArray | string, ...values: any[]): SExpressionTemplateFn;

• returns : myself (template literal function).
• strings : Startup code that evaluate before each evaluation of user code.

appendStartupAST

appendStartupAST(ast: SxToken[]): SExpressionTemplateFn;

• returns : myself (template literal function).
• ast : Startup code AST that evaluate before each evaluation of user code.

install

install(installer: (config: SxParserConfig) => SxParserConfig): SExpressionTemplateFn;

• returns : myself (template literal function).
• installer : Installer function that register the operators, macros, constants to the config object.

runScriptTags

Run script tags.

function runScriptTags(
    lisp: SExpressionTemplateFn | SExpressionAsyncTemplateFn,
    globals?: object,
    contentType = 'text/lisp')

• returns : Evaluation result.
• lisp : Evaluater function.
• globals : Global variables.
• contentType : Content type attribute of script tags.

Usage:

<!DOCTYPE html>
<head>
    <meta charset="utf-8">
    <script type="text/lisp">
        ($local ((body (::document@querySelector "body")))
            ($set (body innerText) "Hello, Lisp! ") )
        ($local (c) ($capture (c)
            ($$defun tarai(x y z)
                ($set c (+ c 1))
                ($if (<= x y)
                    y
                    ($self ($self (- x 1) y z)
                        ($self (- y 1) z x)
                        ($self (- z 1) x y))))
            ($list ($datetime-to-iso-string ($now)) (tarai 13 6 0) c) ))
    </script>
    <script src="liyad.min.js"></script>
    <script>
        // Since the above lisp code refers to the body element,
        // you need to enclose the lisp evaluation with addEventListener.
        document.addEventListener('DOMContentLoaded', function(event) {
            const result = JSON.stringify(
                liyad.runScriptTags(liyad.lisp, {window, document}));
            const body = document.querySelector('body');
            setTimeout(() => body.innerText = body.innerText + result, 30);
        });
    </script>
</head>
<body></body>

---

Tree shaking (webpack)

You can benefit from tree shaking by importing ES module separated files.

Import path	Description
liyad/modules	Entire library
liyad/modules/s-exp/types	Type definitions
liyad/modules/s-exp/interpreter	Interpreter DIY APIs SExpression, SExpressionAsync
liyad/modules/s-exp/interpreter/presets/s-exp	Preset s-expression parser S
liyad/modules/s-exp/interpreter/presets/lisp	Preset interpreters lisp, lisp_async, LM, LM_async
liyad/modules/s-exp/interpreter/presets/lsx	Preset interpreters LSX, LSX_async
liyad/modules/s-exp/operators/core	Core operators
liyad/modules/s-exp/operators/arithmetic	Arithmetic operators
liyad/modules/s-exp/operators/sequence	Sequence operators
liyad/modules/s-exp/operators/concurrent	Concurrent operators
liyad/modules/s-exp/operators/jsx	JSX (LSX) operators

NOTICE: liyad/modules/* are not babelized. These are output as ES2015 by tsc.

---

Operators

See core, arithmetic, sequence, concurrent, JSX (LSX) operators.

---

License

ISC
Copyright (c) 2018, 2019 Shellyl_N and Authors.