Statements and calls

A statement calls a program, reads a named value, creates a scalar alias, or runs a structural block. This page covers program-call syntax.

Call shape

The complete statement form is:

@access name<Type>(arguments) { body } as output

Each part is optional only when the target allows it:

image("title.png", 2s, contain)
concat<Audio>
@visible repeat(2)
during(1s..3s) {
    zoom_in(2%)
}
operation as result
operation as (first, second)
operation as (first, _, third)

• @owned or @visible chooses stack access.
• <Video> or <Audio> selects a generic type.
• (arguments) supplies graph or scalar inputs.
• { body } supplies a body to a body program or language form.
• as output binds one or several output positions.

Output bindings

An output name creates a graph reference and a timeline placement label for its position:

operation as result
operation as (first, second)

Use _ to leave a position unnamed:

operation as (first, _, third)

The wildcard still occupies an output position, so binding arity remains exact. It creates no $_ reference and no _ timeline placement. It also does not discard the value: the unnamed output remains on the stack for later calls. Multiple _ slots are allowed. For a single-output statement, as _ is the explicit wildcard form and has the same stack effect as omitting as.

Omitting empty syntax

At statement position, a zero-argument call may omit ():

concat
repeat(2)

Inside an argument expression, a program call must keep its parentheses:

set_audio(video=video("picture.mp4"), audio=audio("sound.wav"))

An unparenthesized identifier inside an argument is a scalar atom, not a call.

For a construct that accepts a body, omitted braces mean an empty body. These forms are equivalent:

join
join()
join {}
join() {}

Normal input and body-output requirements still apply. Bare join still needs two matching timelines. A direct program that does not accept a body rejects braces.

Generic type selection

The compiler usually infers whether a generic call uses Video or Audio. Write an explicit type when both are accessible or when deliberate selection improves clarity:

concat<Video>
drop<Audio>

See Stack binding for arguments and access modifiers. See Composition forms for clip, blocks, and names. See Built-in programs for exact call shapes.