mono/shared/static/scripts/sexp.js

/**
 * sexp.js — S-expression parser, evaluator, and DOM renderer.
 *
 * Client-side counterpart to shared/sexp/ Python modules.
 * Parses s-expression text, evaluates it, and renders to DOM nodes.
 *
 * Usage:
 *   Sexp.loadComponents('(defcomp ~card (&key title) (div :class "c" title))');
 *   const node = Sexp.render('(~card :title "Hello")');
 *   document.body.appendChild(node);
 */
;(function (global) {
  "use strict";

  // =========================================================================
  // Types
  // =========================================================================

  /** Singleton nil — falsy placeholder. */
  var NIL = Object.freeze({ _nil: true, toString: function () { return "nil"; } });

  function isNil(x) { return x === NIL || x === null || x === undefined; }
  function isTruthy(x) { return x !== false && !isNil(x) && x !== 0 && x !== ""; }
  // Note: 0 and "" are falsy in sexp but we match Python semantics where
  // only nil/false/None are falsy for control flow.  Revisit if needed.
  function isSexpTruthy(x) { return x !== false && !isNil(x); }

  function Symbol(name) { this.name = name; }
  Symbol.prototype.toString = function () { return this.name; };
  Symbol.prototype._sym = true;

  function Keyword(name) { this.name = name; }
  Keyword.prototype.toString = function () { return ":" + this.name; };
  Keyword.prototype._kw = true;

  function Lambda(params, body, closure, name) {
    this.params = params;
    this.body = body;
    this.closure = closure || {};
    this.name = name || null;
  }
  Lambda.prototype._lambda = true;

  function Component(name, params, hasChildren, body, closure) {
    this.name = name;
    this.params = params;
    this.hasChildren = hasChildren;
    this.body = body;
    this.closure = closure || {};
  }
  Component.prototype._component = true;

  /** Marker for pre-rendered HTML that bypasses escaping. */
  function RawHTML(html) { this.html = html; }
  RawHTML.prototype._raw = true;

  function isSym(x) { return x && x._sym === true; }
  function isKw(x) { return x && x._kw === true; }
  function isLambda(x) { return x && x._lambda === true; }
  function isComponent(x) { return x && x._component === true; }
  function isRaw(x) { return x && x._raw === true; }

  // =========================================================================
  // Parser
  // =========================================================================

  var RE_WS = /\s+/y;
  var RE_COMMENT = /;[^\n]*/y;
  var RE_STRING = /"(?:[^"\\]|\\.)*"/y;
  var RE_NUMBER = /-?(?:\d+\.?\d*|\.\d+)(?:[eE][+-]?\d+)?/y;
  var RE_KEYWORD = /:[a-zA-Z_][a-zA-Z0-9_>:\-]*/y;
  var RE_SYMBOL = /[a-zA-Z_~*+\-><=/!?&][a-zA-Z0-9_~*+\-><=/!?.:&]*/y;

  function Tokenizer(text) {
    this.text = text;
    this.pos = 0;
    this.line = 1;
    this.col = 1;
  }

  Tokenizer.prototype._advance = function (count) {
    for (var i = 0; i < count; i++) {
      if (this.pos < this.text.length) {
        if (this.text[this.pos] === "\n") { this.line++; this.col = 1; }
        else { this.col++; }
        this.pos++;
      }
    }
  };

  Tokenizer.prototype._skip = function () {
    while (this.pos < this.text.length) {
      RE_WS.lastIndex = this.pos;
      var m = RE_WS.exec(this.text);
      if (m && m.index === this.pos) { this._advance(m[0].length); continue; }
      RE_COMMENT.lastIndex = this.pos;
      m = RE_COMMENT.exec(this.text);
      if (m && m.index === this.pos) { this._advance(m[0].length); continue; }
      break;
    }
  };

  Tokenizer.prototype.peek = function () {
    this._skip();
    return this.pos < this.text.length ? this.text[this.pos] : null;
  };

  Tokenizer.prototype.next = function () {
    this._skip();
    if (this.pos >= this.text.length) return null;

    var ch = this.text[this.pos];

    // Delimiters
    if ("()[]{}".indexOf(ch) !== -1) { this._advance(1); return ch; }

    // String
    if (ch === '"') {
      RE_STRING.lastIndex = this.pos;
      var m = RE_STRING.exec(this.text);
      if (!m || m.index !== this.pos) throw parseErr("Unterminated string", this);
      this._advance(m[0].length);
      var raw = m[0].slice(1, -1);
      return raw.replace(/\\n/g, "\n").replace(/\\t/g, "\t")
                .replace(/\\"/g, '"').replace(/\\\\/g, "\\");
    }

    // Keyword
    if (ch === ":") {
      RE_KEYWORD.lastIndex = this.pos;
      m = RE_KEYWORD.exec(this.text);
      if (!m || m.index !== this.pos) throw parseErr("Invalid keyword", this);
      this._advance(m[0].length);
      return new Keyword(m[0].slice(1));
    }

    // Number (before symbol due to leading -)
    if (isDigit(ch) || (ch === "-" && this.pos + 1 < this.text.length &&
        (isDigit(this.text[this.pos + 1]) || this.text[this.pos + 1] === "."))) {
      RE_NUMBER.lastIndex = this.pos;
      m = RE_NUMBER.exec(this.text);
      if (m && m.index === this.pos) {
        this._advance(m[0].length);
        var s = m[0];
        return (s.indexOf(".") !== -1 || s.indexOf("e") !== -1 || s.indexOf("E") !== -1)
          ? parseFloat(s) : parseInt(s, 10);
      }
    }

    // Symbol
    RE_SYMBOL.lastIndex = this.pos;
    m = RE_SYMBOL.exec(this.text);
    if (m && m.index === this.pos) {
      this._advance(m[0].length);
      var name = m[0];
      if (name === "true") return true;
      if (name === "false") return false;
      if (name === "nil") return NIL;
      return new Symbol(name);
    }

    throw parseErr("Unexpected character: " + ch, this);
  };

  function isDigit(c) { return c >= "0" && c <= "9"; }

  function parseErr(msg, tok) {
    return new Error(msg + " at line " + tok.line + ", col " + tok.col);
  }

  function parseExpr(tok) {
    var token = tok.next();
    if (token === null) throw parseErr("Unexpected end of input", tok);
    if (token === "(") return parseList(tok, ")");
    if (token === "[") return parseList(tok, "]");
    if (token === "{") return parseMap(tok);
    if (token === ")" || token === "]" || token === "}") {
      throw parseErr("Unexpected " + token, tok);
    }
    return token;
  }

  function parseList(tok, closer) {
    var items = [];
    while (true) {
      var c = tok.peek();
      if (c === null) throw parseErr("Unterminated list, expected " + closer, tok);
      if (c === closer) { tok.next(); return items; }
      items.push(parseExpr(tok));
    }
  }

  function parseMap(tok) {
    var result = {};
    while (true) {
      var c = tok.peek();
      if (c === null) throw parseErr("Unterminated map", tok);
      if (c === "}") { tok.next(); return result; }
      var key = parseExpr(tok);
      var keyStr = isKw(key) ? key.name : String(key);
      result[keyStr] = parseExpr(tok);
    }
  }

  /** Parse a single s-expression. */
  function parse(text) {
    var tok = new Tokenizer(text);
    var result = parseExpr(tok);
    if (tok.peek() !== null) throw parseErr("Unexpected content after expression", tok);
    return result;
  }

  /** Parse zero or more s-expressions. */
  function parseAll(text) {
    var tok = new Tokenizer(text);
    var results = [];
    while (tok.peek() !== null) results.push(parseExpr(tok));
    return results;
  }

  // =========================================================================
  // Primitives
  // =========================================================================

  var PRIMITIVES = {};

  // Arithmetic
  PRIMITIVES["+"] = function () { var s = 0; for (var i = 0; i < arguments.length; i++) s += arguments[i]; return s; };
  PRIMITIVES["-"] = function (a, b) { return arguments.length === 1 ? -a : a - b; };
  PRIMITIVES["*"] = function () { var s = 1; for (var i = 0; i < arguments.length; i++) s *= arguments[i]; return s; };
  PRIMITIVES["/"] = function (a, b) { return a / b; };
  PRIMITIVES["mod"] = function (a, b) { return a % b; };
  PRIMITIVES["inc"] = function (n) { return n + 1; };
  PRIMITIVES["dec"] = function (n) { return n - 1; };
  PRIMITIVES["abs"] = Math.abs;
  PRIMITIVES["floor"] = Math.floor;
  PRIMITIVES["ceil"] = Math.ceil;
  PRIMITIVES["round"] = Math.round;
  PRIMITIVES["min"] = Math.min;
  PRIMITIVES["max"] = Math.max;
  PRIMITIVES["sqrt"] = Math.sqrt;
  PRIMITIVES["pow"] = Math.pow;

  // Comparison
  PRIMITIVES["="] = function (a, b) { return a == b; };  // loose, matches Python sexp
  PRIMITIVES["!="] = function (a, b) { return a != b; };
  PRIMITIVES["<"] = function (a, b) { return a < b; };
  PRIMITIVES[">"] = function (a, b) { return a > b; };
  PRIMITIVES["<="] = function (a, b) { return a <= b; };
  PRIMITIVES[">="] = function (a, b) { return a >= b; };

  // Logic
  PRIMITIVES["not"] = function (x) { return !isSexpTruthy(x); };

  // String
  PRIMITIVES["str"] = function () {
    var parts = [];
    for (var i = 0; i < arguments.length; i++) {
      var v = arguments[i];
      if (isNil(v)) continue;
      parts.push(String(v));
    }
    return parts.join("");
  };
  PRIMITIVES["upper"] = function (s) { return String(s).toUpperCase(); };
  PRIMITIVES["lower"] = function (s) { return String(s).toLowerCase(); };
  PRIMITIVES["trim"] = function (s) { return String(s).trim(); };
  PRIMITIVES["split"] = function (s, sep) { return String(s).split(sep); };
  PRIMITIVES["join"] = function (sep, coll) { return coll.join(sep); };
  PRIMITIVES["starts-with?"] = function (s, p) { return String(s).indexOf(p) === 0; };
  PRIMITIVES["ends-with?"] = function (s, p) { var str = String(s); return str.indexOf(p, str.length - p.length) !== -1; };
  PRIMITIVES["concat"] = function () {
    var out = [];
    for (var i = 0; i < arguments.length; i++) out = out.concat(arguments[i]);
    return out;
  };

  // Predicates
  PRIMITIVES["nil?"] = function (x) { return isNil(x); };
  PRIMITIVES["number?"] = function (x) { return typeof x === "number"; };
  PRIMITIVES["string?"] = function (x) { return typeof x === "string"; };
  PRIMITIVES["list?"] = function (x) { return Array.isArray(x); };
  PRIMITIVES["dict?"] = function (x) { return x !== null && typeof x === "object" && !Array.isArray(x) && !x._sym && !x._kw; };
  PRIMITIVES["empty?"] = function (c) { return !c || (Array.isArray(c) ? c.length === 0 : Object.keys(c).length === 0); };
  PRIMITIVES["contains?"] = function (c, k) { return Array.isArray(c) ? c.indexOf(k) !== -1 : k in c; };
  PRIMITIVES["odd?"] = function (n) { return n % 2 !== 0; };
  PRIMITIVES["even?"] = function (n) { return n % 2 === 0; };
  PRIMITIVES["zero?"] = function (n) { return n === 0; };

  // Collections
  PRIMITIVES["list"] = function () { return Array.prototype.slice.call(arguments); };
  PRIMITIVES["dict"] = function () {
    var d = {};
    for (var i = 0; i < arguments.length - 1; i += 2) d[arguments[i]] = arguments[i + 1];
    return d;
  };
  PRIMITIVES["get"] = function (c, k, def) { var v = (c && c[k]); return v !== undefined ? v : (def !== undefined ? def : NIL); };
  PRIMITIVES["len"] = function (c) { return Array.isArray(c) ? c.length : Object.keys(c).length; };
  PRIMITIVES["first"] = function (c) { return c && c.length > 0 ? c[0] : NIL; };
  PRIMITIVES["last"] = function (c) { return c && c.length > 0 ? c[c.length - 1] : NIL; };
  PRIMITIVES["rest"] = function (c) { return c ? c.slice(1) : []; };
  PRIMITIVES["nth"] = function (c, n) { return c && n < c.length ? c[n] : NIL; };
  PRIMITIVES["cons"] = function (x, c) { return [x].concat(c || []); };
  PRIMITIVES["append"] = function (c, x) { return (c || []).concat([x]); };
  PRIMITIVES["keys"] = function (d) { return Object.keys(d || {}); };
  PRIMITIVES["vals"] = function (d) { var r = []; for (var k in d) r.push(d[k]); return r; };
  PRIMITIVES["merge"] = function () {
    var out = {};
    for (var i = 0; i < arguments.length; i++) { var d = arguments[i]; for (var k in d) out[k] = d[k]; }
    return out;
  };
  PRIMITIVES["assoc"] = function (d) {
    var out = {}; for (var k in d) out[k] = d[k];
    for (var i = 1; i < arguments.length - 1; i += 2) out[arguments[i]] = arguments[i + 1];
    return out;
  };
  PRIMITIVES["range"] = function (a, b, step) {
    var r = []; step = step || 1;
    if (b === undefined) { b = a; a = 0; }
    for (var i = a; step > 0 ? i < b : i > b; i += step) r.push(i);
    return r;
  };

  // =========================================================================
  // Evaluator
  // =========================================================================

  function sexpEval(expr, env) {
    // Literals
    if (typeof expr === "number" || typeof expr === "string" || typeof expr === "boolean") return expr;
    if (isNil(expr)) return NIL;

    // Symbol lookup
    if (isSym(expr)) {
      var name = expr.name;
      if (name in env) return env[name];
      if (name in PRIMITIVES) return PRIMITIVES[name];
      if (name === "true") return true;
      if (name === "false") return false;
      if (name === "nil") return NIL;
      throw new Error("Undefined symbol: " + name);
    }

    // Keyword → its name
    if (isKw(expr)) return expr.name;

    // Dict literal
    if (expr && typeof expr === "object" && !Array.isArray(expr) && !expr._sym && !expr._kw && !expr._raw) {
      var d = {};
      for (var dk in expr) d[dk] = sexpEval(expr[dk], env);
      return d;
    }

    // List
    if (!Array.isArray(expr)) return expr;
    if (expr.length === 0) return [];

    var head = expr[0];

    // Non-callable head → data list
    if (!isSym(head) && !isLambda(head) && !Array.isArray(head)) {
      return expr.map(function (x) { return sexpEval(x, env); });
    }

    // Special forms
    if (isSym(head)) {
      var sf = SPECIAL_FORMS[head.name];
      if (sf) return sf(expr, env);
      var ho = HO_FORMS[head.name];
      if (ho) return ho(expr, env);
    }

    // Function call
    var fn = sexpEval(head, env);
    var args = [];
    for (var ai = 1; ai < expr.length; ai++) args.push(sexpEval(expr[ai], env));

    if (typeof fn === "function") return fn.apply(null, args);
    if (isLambda(fn)) return callLambda(fn, args, env);
    if (isComponent(fn)) return callComponent(fn, expr.slice(1), env);
    throw new Error("Not callable: " + fn);
  }

  function callLambda(fn, args, callerEnv) {
    if (args.length !== fn.params.length) {
      throw new Error((fn.name || "lambda") + " expects " + fn.params.length + " args, got " + args.length);
    }
    var local = merge({}, fn.closure, callerEnv);
    for (var i = 0; i < fn.params.length; i++) local[fn.params[i]] = args[i];
    return sexpEval(fn.body, local);
  }

  function callComponent(comp, rawArgs, env) {
    var kwargs = {}, children = [];
    var i = 0;
    while (i < rawArgs.length) {
      if (isKw(rawArgs[i]) && i + 1 < rawArgs.length) {
        kwargs[rawArgs[i].name] = sexpEval(rawArgs[i + 1], env);
        i += 2;
      } else {
        children.push(sexpEval(rawArgs[i], env));
        i++;
      }
    }
    var local = merge({}, comp.closure, env);
    for (var pi = 0; pi < comp.params.length; pi++) {
      var p = comp.params[pi];
      local[p] = (p in kwargs) ? kwargs[p] : NIL;
    }
    if (comp.hasChildren) local["children"] = children;
    return sexpEval(comp.body, local);
  }

  // --- Special forms -------------------------------------------------------

  var SPECIAL_FORMS = {};

  SPECIAL_FORMS["if"] = function (expr, env) {
    var cond = sexpEval(expr[1], env);
    if (isSexpTruthy(cond)) return sexpEval(expr[2], env);
    return expr.length > 3 ? sexpEval(expr[3], env) : NIL;
  };

  SPECIAL_FORMS["when"] = function (expr, env) {
    if (!isSexpTruthy(sexpEval(expr[1], env))) return NIL;
    var result = NIL;
    for (var i = 2; i < expr.length; i++) result = sexpEval(expr[i], env);
    return result;
  };

  SPECIAL_FORMS["cond"] = function (expr, env) {
    var clauses = expr.slice(1);
    if (!clauses.length) return NIL;
    // Scheme-style
    if (Array.isArray(clauses[0]) && clauses[0].length === 2) {
      for (var i = 0; i < clauses.length; i++) {
        var test = clauses[i][0];
        if ((isSym(test) && (test.name === "else" || test.name === ":else")) ||
            (isKw(test) && test.name === "else")) return sexpEval(clauses[i][1], env);
        if (isSexpTruthy(sexpEval(test, env))) return sexpEval(clauses[i][1], env);
      }
    } else {
      // Clojure-style
      for (var j = 0; j < clauses.length - 1; j += 2) {
        var t = clauses[j];
        if ((isKw(t) && t.name === "else") || (isSym(t) && (t.name === ":else" || t.name === "else")))
          return sexpEval(clauses[j + 1], env);
        if (isSexpTruthy(sexpEval(t, env))) return sexpEval(clauses[j + 1], env);
      }
    }
    return NIL;
  };

  SPECIAL_FORMS["case"] = function (expr, env) {
    var val = sexpEval(expr[1], env);
    for (var i = 2; i < expr.length - 1; i += 2) {
      var t = expr[i];
      if ((isKw(t) && t.name === "else") || (isSym(t) && (t.name === ":else" || t.name === "else")))
        return sexpEval(expr[i + 1], env);
      if (val == sexpEval(t, env)) return sexpEval(expr[i + 1], env);
    }
    return NIL;
  };

  SPECIAL_FORMS["and"] = function (expr, env) {
    var result = true;
    for (var i = 1; i < expr.length; i++) {
      result = sexpEval(expr[i], env);
      if (!isSexpTruthy(result)) return result;
    }
    return result;
  };

  SPECIAL_FORMS["or"] = function (expr, env) {
    var result = false;
    for (var i = 1; i < expr.length; i++) {
      result = sexpEval(expr[i], env);
      if (isSexpTruthy(result)) return result;
    }
    return result;
  };

  SPECIAL_FORMS["let"] = SPECIAL_FORMS["let*"] = function (expr, env) {
    var bindings = expr[1], local = merge({}, env);
    if (Array.isArray(bindings)) {
      if (bindings.length && Array.isArray(bindings[0])) {
        // Scheme-style
        for (var i = 0; i < bindings.length; i++) {
          var vname = isSym(bindings[i][0]) ? bindings[i][0].name : bindings[i][0];
          local[vname] = sexpEval(bindings[i][1], local);
        }
      } else {
        // Clojure-style
        for (var j = 0; j < bindings.length; j += 2) {
          var vn = isSym(bindings[j]) ? bindings[j].name : bindings[j];
          local[vn] = sexpEval(bindings[j + 1], local);
        }
      }
    }
    var result = NIL;
    for (var k = 2; k < expr.length; k++) result = sexpEval(expr[k], local);
    return result;
  };

  SPECIAL_FORMS["lambda"] = SPECIAL_FORMS["fn"] = function (expr, env) {
    var paramsExpr = expr[1], paramNames = [];
    for (var i = 0; i < paramsExpr.length; i++) {
      var p = paramsExpr[i];
      paramNames.push(isSym(p) ? p.name : String(p));
    }
    return new Lambda(paramNames, expr[2], merge({}, env));
  };

  SPECIAL_FORMS["define"] = function (expr, env) {
    var name = expr[1].name;
    var value = sexpEval(expr[2], env);
    if (isLambda(value) && !value.name) value.name = name;
    env[name] = value;
    return value;
  };

  SPECIAL_FORMS["defcomp"] = function (expr, env) {
    var nameSym = expr[1];
    var compName = nameSym.name.replace(/^~/, "");
    var paramsExpr = expr[2];
    var params = [], hasChildren = false, inKey = false;
    for (var i = 0; i < paramsExpr.length; i++) {
      var p = paramsExpr[i];
      if (isSym(p)) {
        if (p.name === "&key") { inKey = true; continue; }
        if (p.name === "&rest") { hasChildren = true; continue; }
        if (inKey || hasChildren) { if (!hasChildren) params.push(p.name); }
        else params.push(p.name);
      }
    }
    var comp = new Component(compName, params, hasChildren, expr[3], merge({}, env));
    env[nameSym.name] = comp;
    return comp;
  };

  SPECIAL_FORMS["begin"] = SPECIAL_FORMS["do"] = function (expr, env) {
    var result = NIL;
    for (var i = 1; i < expr.length; i++) result = sexpEval(expr[i], env);
    return result;
  };

  SPECIAL_FORMS["quote"] = function (expr) { return expr[1]; };

  SPECIAL_FORMS["set!"] = function (expr, env) {
    var v = sexpEval(expr[2], env);
    env[expr[1].name] = v;
    return v;
  };

  SPECIAL_FORMS["->"] = function (expr, env) {
    var result = sexpEval(expr[1], env);
    for (var i = 2; i < expr.length; i++) {
      var form = expr[i];
      var fn, args;
      if (Array.isArray(form)) {
        fn = sexpEval(form[0], env);
        args = [result];
        for (var j = 1; j < form.length; j++) args.push(sexpEval(form[j], env));
      } else {
        fn = sexpEval(form, env);
        args = [result];
      }
      if (typeof fn === "function") result = fn.apply(null, args);
      else if (isLambda(fn)) result = callLambda(fn, args, env);
      else throw new Error("-> form not callable: " + fn);
    }
    return result;
  };

  // --- Higher-order forms --------------------------------------------------

  var HO_FORMS = {};

  HO_FORMS["map"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    return coll.map(function (item) { return isLambda(fn) ? callLambda(fn, [item], env) : fn(item); });
  };

  HO_FORMS["map-indexed"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    return coll.map(function (item, i) { return isLambda(fn) ? callLambda(fn, [i, item], env) : fn(i, item); });
  };

  HO_FORMS["filter"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    return coll.filter(function (item) {
      var r = isLambda(fn) ? callLambda(fn, [item], env) : fn(item);
      return isSexpTruthy(r);
    });
  };

  HO_FORMS["reduce"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), acc = sexpEval(expr[2], env), coll = sexpEval(expr[3], env);
    for (var i = 0; i < coll.length; i++) acc = isLambda(fn) ? callLambda(fn, [acc, coll[i]], env) : fn(acc, coll[i]);
    return acc;
  };

  HO_FORMS["some"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    for (var i = 0; i < coll.length; i++) {
      var r = isLambda(fn) ? callLambda(fn, [coll[i]], env) : fn(coll[i]);
      if (isSexpTruthy(r)) return r;
    }
    return NIL;
  };

  HO_FORMS["every?"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    for (var i = 0; i < coll.length; i++) {
      if (!isSexpTruthy(isLambda(fn) ? callLambda(fn, [coll[i]], env) : fn(coll[i]))) return false;
    }
    return true;
  };

  HO_FORMS["for-each"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    for (var i = 0; i < coll.length; i++) isLambda(fn) ? callLambda(fn, [coll[i]], env) : fn(coll[i]);
    return NIL;
  };

  // =========================================================================
  // DOM Renderer
  // =========================================================================

  var HTML_TAGS = makeSet(
    "html head body title meta link style script base noscript " +
    "header footer main nav aside section article address hgroup " +
    "h1 h2 h3 h4 h5 h6 " +
    "div p blockquote pre figure figcaption ul ol li dl dt dd hr " +
    "a span em strong small s cite q abbr code var samp kbd sub sup " +
    "i b u mark ruby rt rp bdi bdo br wbr time data " +
    "ins del " +
    "img picture source iframe embed object param video audio track canvas map area " +
    "svg math path circle ellipse line polygon polyline rect g defs use text tspan " +
    "clipPath mask linearGradient radialGradient stop filter " +
    "feGaussianBlur feOffset feMerge feMergeNode animate animateTransform " +
    "table thead tbody tfoot tr th td caption colgroup col " +
    "form fieldset legend label input button select option optgroup textarea output " +
    "datalist progress meter details summary dialog template slot"
  );

  var VOID_ELEMENTS = makeSet(
    "area base br col embed hr img input link meta param source track wbr"
  );

  var BOOLEAN_ATTRS = makeSet(
    "async autofocus autoplay checked controls default defer disabled " +
    "formnovalidate hidden inert ismap loop multiple muted nomodule " +
    "novalidate open playsinline readonly required reversed selected"
  );

  // SVG elements that need createElementNS
  var SVG_TAGS = makeSet(
    "svg path circle ellipse line polygon polyline rect g defs use text tspan " +
    "clipPath mask linearGradient radialGradient stop filter " +
    "feGaussianBlur feOffset feMerge feMergeNode animate animateTransform"
  );

  var SVG_NS = "http://www.w3.org/2000/svg";

  /**
   * Render an s-expression to DOM node(s).
   * Returns a DocumentFragment, Element, or Text node.
   */
  function renderDOM(expr, env) {
    // nil / false → empty
    if (isNil(expr) || expr === false || expr === true) return document.createDocumentFragment();

    // Pre-rendered HTML
    if (isRaw(expr)) {
      var tpl = document.createElement("template");
      tpl.innerHTML = expr.html;
      return tpl.content;
    }

    // String → text node
    if (typeof expr === "string") return document.createTextNode(expr);

    // Number → text node
    if (typeof expr === "number") return document.createTextNode(String(expr));

    // Symbol → evaluate then render
    if (isSym(expr)) return renderDOM(sexpEval(expr, env), env);

    // Keyword → text
    if (isKw(expr)) return document.createTextNode(expr.name);

    // Dict → empty
    if (expr && typeof expr === "object" && !Array.isArray(expr)) return document.createDocumentFragment();

    // List → dispatch
    if (Array.isArray(expr)) {
      if (!expr.length) return document.createDocumentFragment();
      return renderList(expr, env);
    }

    return document.createTextNode(String(expr));
  }

  /** Render-aware special forms for DOM output. */
  var RENDER_FORMS = {};

  RENDER_FORMS["if"] = function (expr, env) {
    var cond = sexpEval(expr[1], env);
    if (isSexpTruthy(cond)) return renderDOM(expr[2], env);
    return expr.length > 3 ? renderDOM(expr[3], env) : document.createDocumentFragment();
  };

  RENDER_FORMS["when"] = function (expr, env) {
    if (!isSexpTruthy(sexpEval(expr[1], env))) return document.createDocumentFragment();
    var frag = document.createDocumentFragment();
    for (var i = 2; i < expr.length; i++) frag.appendChild(renderDOM(expr[i], env));
    return frag;
  };

  RENDER_FORMS["cond"] = function (expr, env) {
    var clauses = expr.slice(1);
    if (!clauses.length) return document.createDocumentFragment();
    if (Array.isArray(clauses[0]) && clauses[0].length === 2) {
      for (var i = 0; i < clauses.length; i++) {
        var test = clauses[i][0];
        if ((isSym(test) && (test.name === "else" || test.name === ":else")) ||
            (isKw(test) && test.name === "else")) return renderDOM(clauses[i][1], env);
        if (isSexpTruthy(sexpEval(test, env))) return renderDOM(clauses[i][1], env);
      }
    } else {
      for (var j = 0; j < clauses.length - 1; j += 2) {
        var t = clauses[j];
        if ((isKw(t) && t.name === "else") || (isSym(t) && (t.name === ":else" || t.name === "else")))
          return renderDOM(clauses[j + 1], env);
        if (isSexpTruthy(sexpEval(t, env))) return renderDOM(clauses[j + 1], env);
      }
    }
    return document.createDocumentFragment();
  };

  RENDER_FORMS["let"] = RENDER_FORMS["let*"] = function (expr, env) {
    var bindings = expr[1], local = merge({}, env);
    if (Array.isArray(bindings)) {
      if (bindings.length && Array.isArray(bindings[0])) {
        for (var i = 0; i < bindings.length; i++) {
          local[isSym(bindings[i][0]) ? bindings[i][0].name : bindings[i][0]] = sexpEval(bindings[i][1], local);
        }
      } else {
        for (var j = 0; j < bindings.length; j += 2) {
          local[isSym(bindings[j]) ? bindings[j].name : bindings[j]] = sexpEval(bindings[j + 1], local);
        }
      }
    }
    var frag = document.createDocumentFragment();
    for (var k = 2; k < expr.length; k++) frag.appendChild(renderDOM(expr[k], local));
    return frag;
  };

  RENDER_FORMS["begin"] = RENDER_FORMS["do"] = function (expr, env) {
    var frag = document.createDocumentFragment();
    for (var i = 1; i < expr.length; i++) frag.appendChild(renderDOM(expr[i], env));
    return frag;
  };

  RENDER_FORMS["define"] = function (expr, env) { sexpEval(expr, env); return document.createDocumentFragment(); };
  RENDER_FORMS["defcomp"] = function (expr, env) { sexpEval(expr, env); return document.createDocumentFragment(); };

  RENDER_FORMS["map"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    var frag = document.createDocumentFragment();
    for (var i = 0; i < coll.length; i++) {
      var val = isLambda(fn) ? renderLambdaDOM(fn, [coll[i]], env) : renderDOM(fn(coll[i]), env);
      frag.appendChild(val);
    }
    return frag;
  };

  RENDER_FORMS["map-indexed"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    var frag = document.createDocumentFragment();
    for (var i = 0; i < coll.length; i++) {
      var val = isLambda(fn) ? renderLambdaDOM(fn, [i, coll[i]], env) : renderDOM(fn(i, coll[i]), env);
      frag.appendChild(val);
    }
    return frag;
  };

  RENDER_FORMS["filter"] = function (expr, env) {
    var result = sexpEval(expr, env);
    return renderDOM(result, env);
  };

  RENDER_FORMS["for-each"] = function (expr, env) {
    var fn = sexpEval(expr[1], env), coll = sexpEval(expr[2], env);
    var frag = document.createDocumentFragment();
    for (var i = 0; i < coll.length; i++) {
      var val = isLambda(fn) ? renderLambdaDOM(fn, [coll[i]], env) : renderDOM(fn(coll[i]), env);
      frag.appendChild(val);
    }
    return frag;
  };

  function renderLambdaDOM(fn, args, env) {
    var local = merge({}, fn.closure, env);
    for (var i = 0; i < fn.params.length; i++) local[fn.params[i]] = args[i];
    return renderDOM(fn.body, local);
  }

  function renderComponentDOM(comp, args, env) {
    var kwargs = {}, children = [];
    var i = 0;
    while (i < args.length) {
      if (isKw(args[i]) && i + 1 < args.length) {
        kwargs[args[i].name] = sexpEval(args[i + 1], env);
        i += 2;
      } else {
        children.push(args[i]);
        i++;
      }
    }
    var local = merge({}, comp.closure, env);
    for (var pi = 0; pi < comp.params.length; pi++) {
      var p = comp.params[pi];
      local[p] = (p in kwargs) ? kwargs[p] : NIL;
    }
    if (comp.hasChildren) {
      // Pre-render children to a fragment, wrap as RawHTML for raw! compatibility
      var childFrag = document.createDocumentFragment();
      for (var ci = 0; ci < children.length; ci++) childFrag.appendChild(renderDOM(children[ci], env));
      local["children"] = childFrag;
    }
    return renderDOM(comp.body, local);
  }

  function renderList(expr, env) {
    var head = expr[0];

    if (isSym(head)) {
      var name = head.name;

      // raw! → insert unescaped
      if (name === "raw!") {
        var frag = document.createDocumentFragment();
        for (var ri = 1; ri < expr.length; ri++) {
          var val = sexpEval(expr[ri], env);
          if (typeof val === "string") {
            var tpl = document.createElement("template");
            tpl.innerHTML = val;
            frag.appendChild(tpl.content);
          } else if (val && val.nodeType) {
            // Already a DOM node (e.g. from children fragment)
            frag.appendChild(val.cloneNode ? val.cloneNode(true) : val);
          } else if (!isNil(val)) {
            frag.appendChild(document.createTextNode(String(val)));
          }
        }
        return frag;
      }

      // <> → fragment
      if (name === "<>") {
        var f = document.createDocumentFragment();
        for (var fi = 1; fi < expr.length; fi++) f.appendChild(renderDOM(expr[fi], env));
        return f;
      }

      // Render-aware special forms
      if (RENDER_FORMS[name]) return RENDER_FORMS[name](expr, env);

      // HTML tag
      if (HTML_TAGS[name]) return renderElement(name, expr.slice(1), env);

      // Component
      if (name.charAt(0) === "~") {
        var comp = env[name];
        if (isComponent(comp)) return renderComponentDOM(comp, expr.slice(1), env);
      }

      // Fallback: evaluate then render
      return renderDOM(sexpEval(expr, env), env);
    }

    // Lambda/list head → evaluate
    if (isLambda(head) || Array.isArray(head)) return renderDOM(sexpEval(expr, env), env);

    // Data list
    var dl = document.createDocumentFragment();
    for (var di = 0; di < expr.length; di++) dl.appendChild(renderDOM(expr[di], env));
    return dl;
  }

  function renderElement(tag, args, env) {
    var el = SVG_TAGS[tag]
      ? document.createElementNS(SVG_NS, tag)
      : document.createElement(tag);

    var i = 0;
    while (i < args.length) {
      var arg = args[i];
      if (isKw(arg) && i + 1 < args.length) {
        var attrName = arg.name;
        var attrVal = sexpEval(args[i + 1], env);
        i += 2;
        if (isNil(attrVal) || attrVal === false) continue;
        if (BOOLEAN_ATTRS[attrName]) {
          if (attrVal) el.setAttribute(attrName, "");
        } else if (attrVal === true) {
          el.setAttribute(attrName, "");
        } else {
          el.setAttribute(attrName, String(attrVal));
        }
      } else {
        // Child
        if (!(tag in VOID_ELEMENTS)) {
          el.appendChild(renderDOM(arg, env));
        }
        i++;
      }
    }

    return el;
  }

  // =========================================================================
  // String Renderer (for SSR parity / testing)
  // =========================================================================

  function escapeText(s) { return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;"); }
  function escapeAttr(s) { return s.replace(/&/g, "&amp;").replace(/"/g, "&quot;").replace(/</g, "&lt;").replace(/>/g, "&gt;"); }

  function renderStr(expr, env) {
    if (isNil(expr) || expr === false || expr === true) return "";
    if (isRaw(expr)) return expr.html;
    if (typeof expr === "string") return escapeText(expr);
    if (typeof expr === "number") return escapeText(String(expr));
    if (isSym(expr)) return renderStr(sexpEval(expr, env), env);
    if (isKw(expr)) return escapeText(expr.name);
    if (Array.isArray(expr)) { if (!expr.length) return ""; return renderStrList(expr, env); }
    if (expr && typeof expr === "object") return "";
    return escapeText(String(expr));
  }

  function renderStrList(expr, env) {
    var head = expr[0];
    if (!isSym(head)) {
      var parts = [];
      for (var i = 0; i < expr.length; i++) parts.push(renderStr(expr[i], env));
      return parts.join("");
    }
    var name = head.name;

    if (name === "raw!") {
      var ps = [];
      for (var ri = 1; ri < expr.length; ri++) {
        var v = sexpEval(expr[ri], env);
        if (isRaw(v)) ps.push(v.html);
        else if (typeof v === "string") ps.push(v);
        else if (!isNil(v)) ps.push(String(v));
      }
      return ps.join("");
    }
    if (name === "<>") {
      var fs = [];
      for (var fi = 1; fi < expr.length; fi++) fs.push(renderStr(expr[fi], env));
      return fs.join("");
    }
    if (name === "if") {
      return isSexpTruthy(sexpEval(expr[1], env))
        ? renderStr(expr[2], env)
        : (expr.length > 3 ? renderStr(expr[3], env) : "");
    }
    if (name === "when") {
      if (!isSexpTruthy(sexpEval(expr[1], env))) return "";
      var ws = [];
      for (var wi = 2; wi < expr.length; wi++) ws.push(renderStr(expr[wi], env));
      return ws.join("");
    }
    if (name === "let" || name === "let*") {
      var bindings = expr[1], local = merge({}, env);
      if (Array.isArray(bindings)) {
        if (bindings.length && Array.isArray(bindings[0])) {
          for (var li = 0; li < bindings.length; li++) {
            local[isSym(bindings[li][0]) ? bindings[li][0].name : bindings[li][0]] = sexpEval(bindings[li][1], local);
          }
        } else {
          for (var lj = 0; lj < bindings.length; lj += 2) {
            local[isSym(bindings[lj]) ? bindings[lj].name : bindings[lj]] = sexpEval(bindings[lj + 1], local);
          }
        }
      }
      var ls = [];
      for (var lk = 2; lk < expr.length; lk++) ls.push(renderStr(expr[lk], local));
      return ls.join("");
    }
    if (name === "begin" || name === "do") {
      var bs = [];
      for (var bi = 1; bi < expr.length; bi++) bs.push(renderStr(expr[bi], env));
      return bs.join("");
    }
    if (name === "define" || name === "defcomp") { sexpEval(expr, env); return ""; }

    if (HTML_TAGS[name]) return renderStrElement(name, expr.slice(1), env);

    if (name.charAt(0) === "~") {
      var comp = env[name];
      if (isComponent(comp)) return renderStrComponent(comp, expr.slice(1), env);
    }

    return renderStr(sexpEval(expr, env), env);
  }

  function renderStrElement(tag, args, env) {
    var attrs = [], children = [];
    var i = 0;
    while (i < args.length) {
      if (isKw(args[i]) && i + 1 < args.length) {
        var aname = args[i].name, aval = sexpEval(args[i + 1], env);
        i += 2;
        if (isNil(aval) || aval === false) continue;
        if (BOOLEAN_ATTRS[aname]) { if (aval) attrs.push(" " + aname); }
        else if (aval === true) attrs.push(" " + aname);
        else attrs.push(" " + aname + '="' + escapeAttr(String(aval)) + '"');
      } else {
        children.push(args[i]);
        i++;
      }
    }
    var open = "<" + tag + attrs.join("") + ">";
    if (VOID_ELEMENTS[tag]) return open;
    var inner = [];
    for (var ci = 0; ci < children.length; ci++) inner.push(renderStr(children[ci], env));
    return open + inner.join("") + "</" + tag + ">";
  }

  function renderStrComponent(comp, args, env) {
    var kwargs = {}, children = [];
    var i = 0;
    while (i < args.length) {
      if (isKw(args[i]) && i + 1 < args.length) {
        kwargs[args[i].name] = sexpEval(args[i + 1], env);
        i += 2;
      } else { children.push(args[i]); i++; }
    }
    var local = merge({}, comp.closure, env);
    for (var pi = 0; pi < comp.params.length; pi++) {
      var p = comp.params[pi];
      local[p] = (p in kwargs) ? kwargs[p] : NIL;
    }
    if (comp.hasChildren) {
      var cs = [];
      for (var ci = 0; ci < children.length; ci++) cs.push(renderStr(children[ci], env));
      local["children"] = new RawHTML(cs.join(""));
    }
    return renderStr(comp.body, local);
  }

  // =========================================================================
  // Helpers
  // =========================================================================

  function merge(target) {
    for (var i = 1; i < arguments.length; i++) {
      var src = arguments[i];
      if (src) for (var k in src) target[k] = src[k];
    }
    return target;
  }

  function makeSet(str) {
    var s = {}, parts = str.split(/\s+/);
    for (var i = 0; i < parts.length; i++) if (parts[i]) s[parts[i]] = true;
    return s;
  }

  /** Convert snake_case kwargs to kebab-case for sexp conventions. */
  function toKebab(s) { return s.replace(/_/g, "-"); }

  // =========================================================================
  // Public API
  // =========================================================================

  var _componentEnv = {};

  var Sexp = {
    // Types
    NIL: NIL,
    Symbol: Symbol,
    Keyword: Keyword,

    // Parser
    parse: parse,
    parseAll: parseAll,

    // Evaluator
    eval: function (expr, env) { return sexpEval(expr, env || _componentEnv); },

    // DOM Renderer
    render: function (exprOrText, extraEnv) {
      var expr = typeof exprOrText === "string" ? parse(exprOrText) : exprOrText;
      var env = extraEnv ? merge({}, _componentEnv, extraEnv) : _componentEnv;
      return renderDOM(expr, env);
    },

    // String Renderer (matches Python html.render output)
    renderToString: function (exprOrText, extraEnv) {
      var expr = typeof exprOrText === "string" ? parse(exprOrText) : exprOrText;
      var env = extraEnv ? merge({}, _componentEnv, extraEnv) : _componentEnv;
      return renderStr(expr, env);
    },

    /**
     * Render a named component with keyword args (Python-style API).
     *   Sexp.renderComponent("card", {title: "Hi"})
     */
    renderComponent: function (name, kwargs, extraEnv) {
      var fullName = name.charAt(0) === "~" ? name : "~" + name;
      var env = extraEnv ? merge({}, _componentEnv, extraEnv) : _componentEnv;
      var comp = env[fullName];
      if (!isComponent(comp)) throw new Error("Unknown component: " + fullName);
      // Build a synthetic call expression
      var callExpr = [new Symbol(fullName)];
      if (kwargs) {
        for (var k in kwargs) {
          callExpr.push(new Keyword(toKebab(k)));
          callExpr.push(kwargs[k]);
        }
      }
      return renderDOM(callExpr, env);
    },

    // Component management
    loadComponents: function (text) {
      var exprs = parseAll(text);
      for (var i = 0; i < exprs.length; i++) sexpEval(exprs[i], _componentEnv);
    },

    getEnv: function () { return _componentEnv; },

    // Utility
    isTruthy: isSexpTruthy,
    isNil: isNil,

    /**
     * Mount a sexp expression into a DOM element, replacing its contents.
     *   Sexp.mount(el, '(~card :title "Hi")')
     *   Sexp.mount("#target", '(~card :title "Hi")')
     *   Sexp.mount(el, '(~card :title name)', {name: "Jo"})
     */
    mount: function (target, exprOrText, extraEnv) {
      var el = typeof target === "string" ? document.querySelector(target) : target;
      if (!el) return;
      var node = Sexp.render(exprOrText, extraEnv);
      el.textContent = "";
      el.appendChild(node);
    },

    /**
     * Process all <script type="text/sexp"> tags in the document.
     * Tags with data-components load component definitions.
     * Tags with data-mount="<selector>" render into that element.
     */
    processScripts: function (root) {
      var scripts = (root || document).querySelectorAll('script[type="text/sexp"]');
      for (var i = 0; i < scripts.length; i++) {
        var s = scripts[i];
        if (s._sexpProcessed) continue;
        s._sexpProcessed = true;

        var text = s.textContent;
        if (!text || !text.trim()) continue;

        // data-components: load as component definitions
        if (s.hasAttribute("data-components")) {
          Sexp.loadComponents(text);
          continue;
        }

        // data-mount="<selector>": render into target
        var mountSel = s.getAttribute("data-mount");
        if (mountSel) {
          var target = document.querySelector(mountSel);
          if (target) Sexp.mount(target, text);
          continue;
        }

        // Default: load as components
        Sexp.loadComponents(text);
      }
    },

    /**
     * Bind client-side sexp rendering to elements with data-sexp-* attrs.
     *
     * Pattern:
     *   <div data-sexp="(~card :title title)" data-sexp-env='{"title":"Hi"}'>
     *     <!-- server-rendered HTML (hydration target) -->
     *   </div>
     *
     * Call Sexp.update(el, {title: "New"}) to re-render with new data.
     */
    update: function (target, newEnv) {
      var el = typeof target === "string" ? document.querySelector(target) : target;
      if (!el) return;
      var source = el.getAttribute("data-sexp");
      if (!source) return;
      var baseEnv = {};
      var envAttr = el.getAttribute("data-sexp-env");
      if (envAttr) {
        try { baseEnv = JSON.parse(envAttr); } catch (e) { /* ignore */ }
      }
      var env = merge({}, _componentEnv, baseEnv, newEnv || {});
      var node = renderDOM(parse(source), env);
      el.textContent = "";
      el.appendChild(node);
      if (newEnv) {
        merge(baseEnv, newEnv);
        el.setAttribute("data-sexp-env", JSON.stringify(baseEnv));
      }
    },

    /**
     * Find all [data-sexp] elements within root and render them.
     * Useful after HTMX swaps bring in new sexp-enabled elements.
     */
    hydrate: function (root) {
      var els = (root || document).querySelectorAll("[data-sexp]");
      for (var i = 0; i < els.length; i++) {
        if (els[i]._sexpHydrated) continue;
        els[i]._sexpHydrated = true;
        Sexp.update(els[i]);
      }
    },

    // For testing
    _types: { NIL: NIL, Symbol: Symbol, Keyword: Keyword, Lambda: Lambda, Component: Component, RawHTML: RawHTML },
    _eval: sexpEval,
    _renderStr: renderStr,
    _renderDOM: renderDOM,
  };

  global.Sexp = Sexp;

  // =========================================================================
  // Auto-init in browser
  // =========================================================================

  if (typeof document !== "undefined") {
    var init = function () {
      Sexp.processScripts();
      Sexp.hydrate();
    };
    if (document.readyState === "loading") {
      document.addEventListener("DOMContentLoaded", init);
    } else {
      init();
    }

    // Re-process after HTMX swaps
    document.addEventListener("htmx:afterSwap", function (e) {
      Sexp.processScripts(e.detail.target);
      Sexp.hydrate(e.detail.target);
    });
  }

})(typeof window !== "undefined" ? window : this);