# 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`
`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` · `loop i in a..b` · `loop {}` · `func f(..) {}` · `f(..) => expr` ·
`class C {}` · `model M {}` · `stencil S(..) {}` · `return` · `try/catch` · `import "..."` ·
`>> expr` (= print)

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## Built-in functions

### Core / convert
| Function | Description |
|----------|-------------|
| `print(...)` | print values space-separated + newline |
| `input(prompt?)` | read a line from stdin |
| `type(x)` | type name as string |
| `len(x)` | length of string/list/dict |
| `str(x)` / `repr(x)` | to string |
| `int(x)` `float(x)` `bool(x)` | convert |
| `list(...)` `dict()` | construct |
| `range(n)` / `range(a,b)` / `range(a,b,step)` | list of ints |
| `exit(code)` | stop the program |

### 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)` `http_post(url,body)` · `serve(port,handler)` ·
`tcp_connect(host,port)` `tcp_send(id,data)` `tcp_recv(id)` `tcp_close(id)`

### Database (SQLite)
`db_open(path)` `db_exec(sql)` `db_query(sql)`

### 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()`).

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## 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`