githubBQN.user.js

// ==UserScript==
// @name         BQN highlighting
// @namespace    https://github.com/dzaima
// @version      0.2
// @description  Syntax highlighting for BQN code on GitHub
// @author       dzaima
// @match        https://github.com/*
// @grant        none
// ==/UserScript==

let dark = true;
let prevLink = "";

document.body.classList.add(dark? 'dt' : 'lt');
function upd() {
  'use strict';
  let newLink = window.location.href;
  if (newLink.includes('#')) newLink = newLink.substring(0, newLink.indexOf('#'));
  if (newLink==prevLink || !newLink.endsWith(".bqn")) return;
  if (document.getElementsByClassName("highlight tab-size js-file-line-container").length==0) return;
  prevLink = newLink;
  let fnames = document.getElementsByClassName('final-path');  
  if (fnames.length!=1 || !fnames[0].innerText.endsWith('.bqn')) return;
  let els = [...document.getElementsByClassName("blob-code blob-code-inner js-file-line")];
  if (els.length) {
    let table = document.querySelector("table.highlight.js-file-line-container");
    let tableP = table.parentElement;
    table.remove();
    els.forEach(c=>{
      let txt = [...c.innerText];
      c.innerHTML = colorCode(txt, parseBQN(txt), 'B');
    });
    tableP.appendChild(table);
  }
}

setTimeout(() => {
  setInterval(upd, 1000);
  upd();
}, 1000);



// copy-pasted from paste:
let htmlMap = {};
function html(str) {
  let res = "";
  for (let chr of str) {
    if (chr>='0'&chr<='9' | chr>='a'&chr<='z' | chr>='A'&chr<='Z' | chr==' ' | chr=='_') res+= chr;
    else if (chr=='\n') res+= '<br>';
    else {
      let m = htmlMap[chr];
      if (!m) m = htmlMap[chr] = new Option(chr).innerHTML;
      res+= m;
    }
  }
  return res;
}
function colorCode(str, cols, prefix) {
  const wrap = (sub,col) => `<span class=${prefix+col}>${html(sub)}</span>`;
  let code = "";
  let pcol = cols[0];
  let li = 0;
  for (let i = 0; i < str.length; i++) {
    let ncol = cols[i];
    if (ncol && pcol!=ncol) {
      code+= wrap(str.slice(li,i), pcol);
      li = i;
      pcol = ncol;
    }
  }
  if (pcol) code+= wrap(str.slice(li), pcol);
  return code;
}

function parseBQN(str) {
  str = str;
  const regC = '0';
  const fnsC = '1'; let   fns = "!+-×÷⋆*√⌊⌈∧∨¬|=≠≤<>≥≡≢⊣⊢⥊∾≍⋈↑↓↕⌽⍉/⍋⍒⊏⊑⊐⊒∊⍷⊔«»⍎⍕";
  const mopC = '2'; let   mop = "`˜˘¨⁼⌜´˝˙";
  const dopC = '3'; const dop = "∘⊸⟜○⌾⎉⚇⍟⊘◶⎊";
  const namC = '4'; const nam = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_";
  const digC = '5'; const dig = "0123456789π∞"; const digS = dig+"¯."; const digM = "eEiI";
  const arrC = '6'; const arr = "·⍬‿⦃⦄⟨⟩[]@";
  const dfnC = '7'; const dfn = [..."𝕨𝕩𝔽𝔾𝕎𝕏𝕗𝕘𝕣ℝ𝕤𝕊{}:"]; // double-strucks are 2-byters
  const strC = '8'; // '' ""
  const dmdC = 'D'; const dmd = "←↩,⋄→⇐";
  const comC = 'C'; // #
  if (!window.BQNStyle) {
    const s = document.createElement("style");
    s.id = "BQNStyle";
    s.innerText=`
      body.dt .B${regC} { color: #D2D2D2; }  body.lt .B${regC} { color: #000000; }
      body.dt .B${namC} { color: #D2D2D2; }  body.lt .B${namC} { color: #000000; }
      body.dt .B${comC} { color: #898989; }  body.lt .B${comC} { color: #6A737D; }
      body.dt .B${digC} { color: #ff6E6E; }  body.lt .B${digC} { color: #005CC5; }
      body.dt .B${arrC} { color: #DD99FF; }  body.lt .B${arrC} { color: #005CC5; }
      body.dt .B${dmdC} { color: #FFFF00; }  body.lt .B${dmdC} { color: #0000FF; }
      body.dt .B${strC} { color: #6A9FFB; }  body.lt .B${strC} { color: #032F62; }
      body.dt .B${fnsC} { color: #57d657; }  body.lt .B${fnsC} { color: #D73A49; }
      body.dt .B${mopC} { color: #EB60DB; }  body.lt .B${mopC} { color: #ED5F00; }
      body.dt .B${dopC} { color: #FFDD66; }  body.lt .B${dopC} { color: #C82C00; }
      body.dt .B${dfnC} { color: #AA77BB; }  body.lt .B${dfnC} { color: #A906D4; }
    `;
    document.body.appendChild(s);
  }
  const res = new Array(str.length).fill();
  res[0] = regC;
  for (let i = 0; i < str.length; ) {
    const p = str[i-1]||'\0';
    const c = str[i  ];
    const n = str[i+1]||'\0';
    
    if (digS.includes(c)) {
      res[i] = digC; i++;
      while(dig.includes(str[i]) || str[i]=='.' || digM.includes(str[i])&&digS.includes(str[i+1])) i++;
      continue;
    }
    else if (fns.includes(c)) res[i] = fnsC;
    else if (mop.includes(c)) res[i] = mopC;
    else if (dop.includes(c)) res[i] = dopC;
    else if (dfn.includes(c)) res[i] = dfnC;
    else if (arr.includes(c)) res[i] = arrC;
    else if (dmd.includes(c)) res[i] = dmdC;
    else if (nam.includes(c) || c=='•') {
      let fst = i;
      if (str[i] == '•') i++;
      let cs = str[i];
      while(nam.includes(str[i]) || dig.includes(str[i])) i++;
      let ce = str[i-1];
      res[fst] = cs=='_'? (ce=='_'? dopC : mopC) : (cs>='A'&&cs<='Z'?fnsC : namC);
      continue;
    }
    else if (c=="'" || c=='"') {
      res[i] = strC; i++;
      let q = c;
      while(str[i] && str[i]!=q && str[i]!='\n') i++;
    }
    else if (c=='#') {
      res[i] = comC;
      while(str[i] && str[i]!='\n') i++;
    }
    else if (!' \n\t'.includes(c)) res[i] = regC;
    i++;
  }
  return res;
}

Hello,

Just wanted You to be aware: Based on the above script (thank You for providing this, by the way!) and the already-existing APL support in the project, I have made a pull request to add BQN support to PrismJS (mostly because I want to post BQN code in my blog).