Skip to main content

Cells and functions

Cells and functions look alike but do different jobs: a cell describes layout, a function computes a value.

Cells​

A cell describes layout and can be placed inside other cells:

cell pad(width: Float, height: Float) {
    rect("met1", x0=0., y0=0., w=width, h=height);
}

Calling pad(100., 80.) gives you a cell value. Pass it to inst to place it.

Functions​

A function computes a value. Its last expression is the return value:

fn half(value: Float) -> Float {
    value / 2.
}

A function can also emit geometry or constraints into the scope it's called from:

fn align_left(a: Rect, b: Rect) {
    eq(a.x0, b.x0);
}

Arguments and return types​

Argument types are written name: Type, and the return type follows ->. Some argument types can be inferred, but writing them out gives clearer call sites and error messages.

fn inset_bounds(rect_: Rect, amount: Float) -> Rect {
    crect(
        x0=rect_.x0 + amount,
        y0=rect_.y0 + amount,
        x1=rect_.x1 - amount,
        y1=rect_.y1 - amount,
    )
}

Bindings and order​

let introduces an immutable binding:

let bounds = bbox(child);

Top-level declarations are resolved across the whole module, so a cell can call a function declared further down the file.