Values and syntax¶

Scalars¶

# Drone light show, New Year's Eve.
lights = TWINKLE
drones = 120
wind_correction = -0.125
title = "Happy New Year"
formation = SPIRAL
choreography = ./shows/midnight.csv

A flag that names a state, such as lights_on = true, reads better as an enum. lights = TWINKLE says what happens, and lights = STROBE fits in later without renaming the setting.

Numbers use decimal notation, optionally with an exponent: 1.5e-7, and a quantity such as 1.5e-3m. A number with an exponent is always a float, 3e2 included. The exponent needs digits, so 1Em is still one exametre. A number or unit conversion that overflows is an error.

Quoted strings are raw: backslashes stay as written, and a quote ends the string. The parser accepts multiline strings. The value serializer rejects strings containing quotes or newlines because it cannot represent them safely.

An unquoted path extends to the next space or newline. Delimiters immediately after a path become part of that path. Use strings for path-like values inside arrays when you need surrounding punctuation.

Arrays and matrices¶

colors = ["gold", "white"]
launch_delays = [0s, 200ms, 400ms]
formation_rotation = [[1, 0, 0],
                      [0, 1, 0],
                      [0, 0, 1]]

Arrays can be nested and may have a trailing comma. Put continuation newlines after commas. The language permits mixed arrays. A schema or Rust target type can require consistent element types.

Ranges¶

altitude = 80m..120m
warmup = 5s..
payload = ..250g
wind = ..
drone_ids = 1..120
brightness = 0.25..0.75

Either bound can be omitted. A range is a pair of optional limits, rather than an arithmetic expression. Use the same physical dimension at both ends. Integer/float mixed endpoints are rejected. The serde Range<T> wrapper keeps missing bounds as None.

Assignments and references¶

spacing = 1.5m
safety_gap = spacing
spacing = 2m
left_wing, right_wing = 10m, 20m
fade_in, fade_out = 500ms

Settings are mutable. References copy the value available at assignment time: safety_gap remains 1.5m in this example. Multiple keys can receive paired values or share one broadcast value. Names begin with an ASCII letter, _, or : and may contain letters, digits, underscores, and colons. Use . to separate namespaces. An initial _ conventionally marks an internal application setting.