Language Reference

This page documents the public Rune language surface shipping today: script(version=1).

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Script Header

Every Rune script starts with script(...):

script(name="My Script", version=1, mode=indicator, overlay=true)

Supported header keys:

Key	Values	Notes
`name`	string	Display name for the script
`version`	`1`	Launch Rune version
`mode`	`indicator`, `strategy`	Default is `indicator`
`overlay`	`true`, `false`	`true` draws over price, `false` uses a sub-pane

Additional numeric and boolean header keys are treated as backtest defaults when the script runs as a strategy. Common examples include:

initial_capital
commission_pct
fee_discount_pct
size_pct
reverse
hedging
pyramiding
max_entries

Parameters

Parameters create editor controls and runtime inputs.

param fast = int("Fast EMA", 20, min=1, max=200, group="Trend")
param mode = string("Mode", "ATR", options=["ATR", "Percent"], group="Entry")
param accent = color("Accent", "#00E676", group="Style")

Parameter Types

Type	Description
`int` / `integer`	Whole-number input
`float` / `number`	Decimal input
`bool` / `boolean`	True/false toggle
`string`	Text input, optionally constrained with `options=[...]`
`color`	Color picker / color value
`timeframe`	Timeframe selector
`session`	Trading session window like `"0900-1700"`
`source`	Source selector
`symbol`	Symbol selector

Common Parameter Options

Option	Description
`label`	Display label
`default`	Default value
`min` / `max`	Numeric bounds
`step`	Numeric step size
`hint`	Tooltip/help text
`group`	Group label in the UI
`options`	Allowed option list for `string`, `timeframe`, and similar selector params

Streams

Streams bind OHLCV data into the script.

stream market = ohlcv()
stream htf = ohlcv(timeframe="15m")
stream external = ohlcv(exchange="blofin", symbol="ETH-USDT", bar="1H")

Supported Forms

Form	Meaning
`ohlcv()`	Current chart candles
`ohlcv(timeframe="15m")`	Same instrument, higher/same timeframe
`ohlcv(timeframe=higher_tf)`	Same instrument, expression-backed timeframe
`ohlcv(bar="1H")`	Alias for `timeframe=...`
`ohlcv(exchange="...", symbol="...", timeframe="...")`	External OHLCV feed supplied by the host runtime

Rules:

timeframe, bar, exchange, and symbol may come from literals or params
external or lower-timeframe streams require host-supplied candles through streamSources / streamCandles
same-timeframe and higher-timeframe internal streams can be auto-aligned from chart candles
stream aliases expose .time, .open, .high, .low, .close, and .volume

Top-Level Blocks

Rune supports these top-level declarations:

script(...)
param ...
stream ...
keep ...
helper calc blocks
panel ...:
risk:
bar:

`keep`

keep declares persistent state that survives from bar to bar.

keep breakout_side = 0
keep trend_count = 0

Update kept state with set inside bar:.

Helper `calc` Blocks

Top-level calc blocks declare reusable pure helper functions:

calc rising(current, prior):
  return current > prior

Helper functions:

are pure
support positional and named arguments
may return tuples
may only use return inside helper blocks

`panel`

Panels provide lightweight dashboards in preview and backtest results.

panel status:
  title "Trend"
  metric fast = ema(close, 20) format="price"
  status bias = close > ema(close, 50) tone="success"
  trade_log limit=5

`risk:`

Strategy scripts can declare top-level portfolio risk controls:

risk:
  max_open_positions = 1
  daily_loss_limit = equity_pct(2)
  daily_trade_limit = 4
  reset_tz = "UTC"

The `bar:` Section

bar: contains the per-candle logic.

bar:
  let fast = ema(close, 20)
  guard trend_ok = close > fast
  signal long = trend_ok
  alert breakout = long
  draw(type=line, series=fast, color=signal_long)

Supported Statements in `bar:`

Statement	Purpose
`let name = expr`	Derived value
`calc name = expr`	Alias assignment form for derived values
`set name = expr`	Update a `keep` value
`guard name = expr`	Named boolean condition
`rule name:` + `require ...`	AND-composed rule block
`flag name = expr`	Named boolean series
`signal name = expr`	Alias for `flag`
`alert name = expr`	Named alert series
`draw(...)`	Declarative chart rendering
`trade(...)`	Entries and exits in strategy mode
`protect(...)`	Managed stop/take updates in strategy mode

Named and Positional Arguments

Expression calls support both positional and named arguments:

let fast = ema(close, 20)
let day_vwap = vwap(reset="day", tz="UTC")
let stamp = timestamp(year=2026, month=4, day=5, hour=12, minute=30, tz="UTC")

Rules:

positional arguments may come first
after the first named argument, all remaining arguments must be named
duplicate named arguments are invalid
unknown named arguments are rejected

Tuple Assignment

Tuple returns can be unpacked directly:

let macd_line, signal_line, hist = macd(close, 12, 26, 9)
let upper, basis, lower = bbands(close, 20, 2)

Guards and Rules

guard is a named boolean series. rule groups multiple require lines into one named setup.

bar:
  guard trend_ok = close > ema(close, 50)
 
  rule long_setup:
    require trend_ok
    require volume > sma(volume, 20)
 
  signal long = long_setup

Rules:

guards and rules can reference earlier calculations and earlier guards/rules
they cannot reference future declarations
rule bodies may not contain side effects

Strategy Statements

Strategy mode adds:

trade(...)
protect(...)
position-state builtins such as position_avg_entry(...) and position_open_r(...)
optional risk: blocks

See Strategies & Backtesting for the full trade model.

Deliberate Non-Goals

Rune does not currently support:

loops
maps or dictionaries, or array literals — the only collection is the chart-only bounded list
imports or modules
imperative drawing APIs like line.new(...) or label.new(...)
Pine namespaces like strategy.* or request.security(...)

That is intentional. Rune stays declarative and product-focused.

Overview

Built-in Functions