16. Complete Reference

A full cheat-sheet of every keyword, operator, and built-in function in STencil.

Keywords

let mut var func return if elif else while for in loop break continue class model new this stencil import try catch true false null and or not

Literals

• int: 42, -7, hex 0xFF (= 255)
• float: 3.14, 4.0
• string: "hi", 'hi', f-string f"x={1+1}"
• bool: true false • null: null
• list: [1, 2, 3] • dict: { "k": v }

Operators

• arithmetic: + - * / %
• comparison: == != < <= > >=
• logic: && || ! (aliases and or not)
• ternary: cond ? a : b
• membership: x in coll
• range: a..b (in loop i in a..b)
• stencil stamp: Name!(args) (single), Name!*list (map)
• index/member: x[i], obj.field, obj.method()

Statements

let/mut/var name = expr · name = expr · if/elif/else · while · for(init;cond;inc) · for x in iter · for i in a..b · loop i in a..b · loop {} · break · continue · func f(..) {} · f(..) => expr · class C {} · model M {} · stencil S(..) {} · return · try/catch · import "..." · >> expr (= print)

Built-in functions

Core / convert

Math

abs round floor ceil pow(a,b) sqrt sin cos tan log log10 exp min(list-or-args) max(list-or-args) sum(list)

Random

random() / rand() (0..1) · randint(a,b) (inclusive) · choice(list) · shuffle(list)

Strings

upper lower trim split(s,sep) join(list,sep) contains(coll,x) reversed(list-or-string) sorted(list) Methods: s.upper() s.lower() s.len() · index s[i]

Lists (methods)

a.push(x) a.append(x) a.pop() a.len() · index read/write a[i] / a[i] = v

Dicts (methods)

d.keys() d.values() d.has(k) d.len() · d[k] / d[k] = v

Files

read_file(p) write_file(p,text) append_file(p,text) file_exists(p) delete_file(p) list_dir(p) make_dir(p)

OS

args() env(name) cwd() exec(cmd) exit(code)

JSON

json_parse(str) json_str(value) json_pretty(value)

Regex

regex_match(p,t) regex_find(p,t) regex_find_all(p,t) regex_replace(p,t,repl)

Date / time

now() (ms) timestamp() (s) date() date_format(fmt) ticks() (ms since start)

Networking

http_get(url, headers?) http_post(url,body,content_type_or_headers?) · serve(port,handler) (single-threaded, sequential) · tcp_connect(host,port) tcp_send(id,data) tcp_recv(id) tcp_close(id)

Database (SQLite)

db_open(path) db_exec(sql, params?) db_query(sql, params?) — bind ? placeholders with a params list to avoid SQL injection.

Terminal graphics

game_init() game_end() clear() draw(x,y,text) / at(x,y,text) color(text,name) sleep(ms) ticks() screen_size() key()

Pixel window graphics

window_open(w,h,title) fill(color) pixel(x,y,color) rect(x,y,w,h,color) window_update() window_is_open() window_key(name) window_mouse() window_mouse_down() window_close()

Sound

beep(freq_hz, ms)

Colors (names for color/fill/rect/pixel)

red green blue white black yellow cyan magenta gray orange — or an int like 0x101828.

Key names (key(), window_key())

up down left right space enter esc and letters w a s d q e r f (more for key()).

Constants

math.pi, math.e

CLI

stencil file.st · stencil -c "code" · stencil (REPL) · stencil build file.st -o out.exe · stencil init · stencil install · stencil --version · stencil --help

Notes

• Type annotations (let x: int = 5, func f(a: string)) are documentation only. STencil is dynamically typed by design — annotations are never enforced.
• Error messages — runtime, syntax, CLI, and installer — are all in English.
• serve is single-threaded and sequential; it's fine for small apps and APIs but will bottleneck under high traffic.