Functions and expressions

Functions

function isLate(moment: time): bool
    return not moment.between(opensAt, closesAt)
end

• Parameter and return types are written. A function with a return type must return on every path; the compiler checks.
• A function may read and write fields and memory, goto, start and stop timers, log and use random; it cannot wait.
• Recursion is allowed; its depth is limited by the budget.
• Functions are declared at the script's level.

Statements

let total = business.visitors + 1          // type inferred, immutable
var count = 0                              // mutable
if total > 100 and not hasPower
    goto Closed
elseif total == 0
    log("empty")
else
    business.visitors = total
end
while count < 3
    count += 1
end
for i in 1 to 10          // 1..10 inclusive
    ring()
end
if count == 0 then return
let shade = if lit then onColor else offColor

• if … then … is the one-line form; if a then b else c is also an expression.
• for i in a to b evaluates its bounds once, does not run when a > b, and i cannot be changed in the body.
• break, continue and return work as usual.
• Assignment is =, +=, -=, *=, /=. The target is a local var, memory or a writes field.

Operators

From the highest precedence to the lowest:

Operators
call, .	clock().between(a, b)
as	speed as int
unary -	-x
* / %
+ -	x-1 is always a subtraction
== != < <= > >=	comparisons do not chain
not	not a == b means not (a == b)
and	short-circuits
or	short-circuits

a.f(b) is the same as f(a, b): clock().between(opensAt, closesAt), neonColor.scaled(0.5).

Operands and arguments are evaluated left to right; in a compound assignment the target first, then the right side.

log

log(...) (server) writes to Play's log with the world's time. {expression} inserts a value:

log("closing, {business.visitors} visitors today")

A transaction logs at most 20 lines of 400 characters; more is cut and marked. Logging does not change behaviour, and lines of a transaction that fails are kept, marked as failed.