Lexical structure

Comments

// A line comment.
/* A block
   comment. */
/// A documentation comment: describes the declaration right below it.
property opensAt: time = 18:00 "Opens"

/// is a documentation comment: it belongs to the declaration below it and becomes its description and tooltip in the editor.

Lines and blocks

• The end of a line ends a statement; there are no semicolons.
• Line breaks inside parentheses, empty lines and lines holding only a comment are ignored.
• Every block closes with a single end. A missing end is reported with the kind of block that was opened and its line.

if hasPower
    decide()
end

Case

Kalem is case-sensitive. Script, host type and state names are PascalCase (BusinessHours, Open); other names are camelCase (opensAt, hasPower).

Reserved words

server client script extends group property memory reads writes input timer daily every
at after on ready enter exit migrate function state auto goto start stop let var if then
elseif else end while for in to break continue return and or not true false as

• Type names are reserved too: bool int float string time duration color.
• Reserved for the next version: task run cancel wait until timeout checkpoint scope send ref none struct list map.
• These mean something only in their own declaration and may be names elsewhere: label category version range step hidden was.

Names

• A name starts with a letter or _ and goes on with letters, digits and _.
• Contract field and event names are dotted: business.open, city.powerChanged. The parts after a dot may be reserved words (light.color, door.state); the first part may not.
• A name resolves first to the declared fields and the catalog's events.
• There is no shadowing. A local or a parameter cannot have the name of anything declared at the script's level (a property, memory, a function), of the standard library, or of the first part of a declared dotted name (business).

Literals

Type	Example	Note
int	42, 0x2A, 1_000
float	0.7, 1.5e3	digits on both sides of the point
string	"Opens", "line\n"	escapes \n \t \\ \" \{; {expression} inserts a value
bool	true, false
time	18:00, 03:30	minute of the day (0–1439); shown as HH:MM in the editor
duration	30m, 2h, 1d, 1h30m	whole minutes
color	#ffd580, #ffd58080	RGB (alpha 1) or RGBA; channel = hex value / 255

In a string, {expression} inserts that expression's value: "{business.visitors} visitors today". A brace itself is written \{.