Library

Numbers

Function
min(a, b), max(a, b)
clamp(x, lo, hi)	lo > hi is an error
abs(x)
floor(x), ceil(x), round(x)	round rounds halves away from zero; a result that does not fit an int is an error
sqrt(x)
mod(a, b)	0 … b-1 for b > 0: mod(-7, 3) == 2; b ≤ 0 is an error

Strings

Function
length(s)	in code points
contains(s, part)
slice(s, from, to)	in code points

Time

Function
now()	the world's minute (int)
clock()	the time of day (time)
hour(t), minute(t)
t.between(a, b)	whether t is in [a, b); may pass midnight (22:00–06:00); a == b is always false

Colours

Colour channels are on a 0–1 scale; c.r, c.g, c.b, c.a read them.

Function
rgb(r, g, b), rgba(r, g, b, a)	rgb(1, 0.5, 0) is orange
mix(a, b, t)	a + (b − a) × t on all four channels
scaled(c, f)	RGB × f
multiply(a, b)	RGB channel by channel; the alpha is a's
withAlpha(c, a)

Server only

Function
random()	a float in [0, 1)
random(a, b)	an int from a to b, both included; a > b is an error
log(...)	writes to Play's log (log)

Client only

sin(x), cos(x) and pi. They give the same result on every platform.

Caria's calendar

Caria's year has 12 months of 28 days: four weeks a month, and every month's 1st is a Monday, so the day of the month decides the day of the week. A year is 336 days, with no leap years and no 29th–31st; years count from 1. A world starts at a date and a time (its .world document's start), and the date is computed from the world's minute. The calendar is the game's, not the language's; the server gives it as functions that read the world's clock.

Function
year()	the game year, from 1
month()	1 January … 12 December
day()	the day of the month, 1–28
weekday()	1 Monday … 7 Sunday
season()	"spring" (March–May), "summer" (June–August), "autumn" (September–November), "winter" (December–February)

There is no list of holidays: a holiday differs by building and by person, and each checks the date in its own script (month() == 10 and day() == 28).

on timer cut
    // No maintenance cut on Sundays or in summer.
    if weekday() != 7 and season() != "summer"
        power.on = false
    end
end

Effects

Every function has an effect; the compiler follows it through calls.

Effect	Meaning	Examples
pure	depends only on its arguments	numbers, strings, colours, between; sin cos pi on the client
read	reads the world or the clock	now clock, the calendar
transactional	writes to the transaction's record; undone with it	random
diagnostic	changes no behaviour and is not undone	log

• A client apply may call only pure functions.
• enter and exit cannot reach goto.
• A function never hands back a live object of the game, only values; the world changes only through the transaction and the script's writes.
• An expected outcome of the game ("no route") is a return value, not an error.