|npx

reference

values

42 3.14 "text {expr}" yes no none [1, 2] { name: "x" } 1..10 fn x -> x * 2

names

x = 1 can't change. mut n = 0 then n <- n + 1 can. [a, b] = pair and { name } = user take values apart.

functions

fn name a b = body, with optional types: fn add a:int b:int -> int = a + b. Types: int num text bool list rec fn none job any. ret returns early.

control

if c then a else b or an indented block, match, for x in xs, while c, break, next

truth

Only no and none count as false. 0 and "" are values like any other.

lists

map keep drop each fold find any all count sum min max first last take skip slice reverse sort sort_by uniq uniq_by flat zip push enum has len index_of chunk window group_by count_by sum_by min_by max_by

text

split join lines chars upper lower trim replace starts ends pad has len text int num

records

keys values get set has, { ...r, x: 1 }, r1 + r2

big numbers

Whole numbers of any size: 123n, 0xffn, big "1234…". + - * // % and comparisons work, mixing with whole numbers; bit operations too. big_le bytes and le_bytes n x convert to and from little-endian bytes. Type big.

bits

xor band bor bnot shl shr rotl rotr add32 sub32 mul32 u32 bits hex32. All work on unsigned 32-bit words.

bytes

hex unhex utf8 unutf8 words unwords, where bytes are a list of numbers 0 to 255

streams

Live values that flow through pipes: sources every ms, events "name" emitter (any JS event emitter, a discord.js client included), stream list, merge [s1, s2]. map keep drop take skip work on streams; window n, debounce ms, throttle ms. s | each f runs it in the background and gives a job (wait job, stop job); collect s and fold wait for the end. A failing item is reported and the stream carries on.

web server

On the command line, use ~/io/http: http.serve 8080 (http.router { "GET /users/:id": fn req -> { id: req.params.id } }). Handlers return text, a record (sent as JSON), { status, body, headers } or none. A failing handler answers 500 and the server keeps running.

tests

Top-level functions named test_… in *_test.npx files are tests: fn test_add = expect (add 1 2) 3. expect_fail f checks that f fails. Run them with npx --test.

command line

npx file.npx runs a program; npx --test, npx --check, npx --fmt, npx --trace, npx --audit; npx --build file.npx makes one .mjs file that runs with plain node, for copying to a server, and npx --build --exe file.npx one program file with Node inside; npx --js shows the compiled JavaScript; npx alone opens a prompt.

trace

The Trace button (or npx --trace file.npx) runs the program and shows the value after every | stage, with its line, so you can watch data flow through a pipeline.

format

The Format button (or npx --fmt file.npx) lays code out the standard way: 2-space indentation, spaces around operators and after commas. It never changes what the code does. npx --fmt --verify only reports, for CI.

playground

main.npx runs; + adds a file that main.npx loads with use ./name. The JavaScript tab shows what the open file compiles to. Share keeps every file. Keys: ctrl+enter runs, ctrl+s formats, ctrl+/ comments lines.

web pages

use ~/io/page: a page is a function that answers elements; after every click or keystroke npx calls it again and updates what changed. page.show view, page.div [kids], page.h1, page.p, page.row, page.list, page.button "label" f, page.input { value, on_input: fn text -> … }, page.link, page.img, page.el tag props kids, page.style css, page.refresh(). It shows in the Page tab here; npx --build --web file.npx makes a standalone .html.

shared libraries

On the command line, npx --add github:user/repo adds a library anyone published, pinned in npx.json; then use lib/name. npx --install fetches them again and checks nothing changed.

check

The Check button (or npx --check) finds likely mistakes without running: too many arguments, a call on its own line missing arguments, type mistakes it can be sure of (text plus a number, a record field that doesn't exist, the wrong type for a typed parameter or -> type, comparing text with a number), a value named like a built-in then called, unused names and use lines (start a name with _ to keep it unused on purpose).

audit

The Audit button (or npx --audit file.npx) lists what a program can touch (network hosts, files, environment variables, npm and Node modules, background work) without running it, following into libraries. allow net "discord.com" lines at the top of a file lock it to exactly that; anything else is refused. Kinds: net, read, write, env, npm, node.

other

print show type fail attempt wait tap range repeat chunk round floor ceil abs. attempt f runs f and returns { ok, value } or { ok: no, error }, catching bugs too.

npx libraries

use npx/discord: Discord bots as one record (commands, slash commands, events), with replies returned not sent, intents worked out for you, cooldowns, admin-only commands, and discord.test to try a bot without Discord. use npx/fetch: HTTP with JSON in and out, timeouts and retries: api = fetch.client { base: "https://…" }, api.get "/users/1", api.post "/users" { name: "aku" }, and fetch.fake for tests without a network. Beta, tested against stand-ins but not yet against the real services: use npx/csv: csv.parse text gives records (header row as field names), csv.text records writes CSV. use npx/mail (command line): post.send { to, subject, text } through Resend or SMTP. use npx/stripe (command line): Stripe payments. use npx/s3, npx/sheets (command line, beta): file storage on any S3-compatible service, and Google Sheets as records. use npx/kv: a key-value store, store.add "coins:aku" 25, store.set_for 60000 "cooldown:aku" yes, store.top "coins:" 3; kv.memory() here, kv.open "bot.json" on the command line. use npx/ai: model.ask, model.chat and model.json for Claude and OpenAI-style APIs, with ai.fake for tests. use npx/telegram: Telegram bots as one record (commands, buttons, on.message), nothing to install, telegram.test bot "/start" to try one. use npx/cron: scheduled jobs, cron.run "0 9 * * mon-fri" f, cron.run "every 5m" f, { when: …, zone: "Europe/Berlin" } for another time zone, daylight saving included, cron.upcoming to test a schedule. use npx/db (command line): SQLite with records in and out, bank.insert "users" { name: "aku" }, bank.find "users" { vip: yes }, transactions. use npx/lattice: the LATTICE cipher.

npm

use npm/pkg loads any npm package; use node/fs loads Node's own modules (command line). Calling a JS class builds an object; JS methods, getters, promises and Map/Set loops work; npx functions passed to JS become callbacks: pure ones answer immediately (so array.sort and lodash work), others answer with a promise (events, async APIs). type of a JS object is js. JavaScript's globals are in ~/io/js: js.Date(), js.Map().

~/io

net (get post json request query), json (parse text pretty), math (with bytes for random bytes), time (now sleep date), date (now parse iso day parts add_days add_hours days_between). Command line only: fs (read write list exists), sys (args env exit).