@by_ref

@by_ref makes a block of this kind reify to a resolvable reference instead of inlining its body at the use site. The value is carried on a record and rendered (or resolved) elsewhere, which keeps cross-cutting definitions in one place.

@by_ref @block("color") type Color {
  @inline(0) name: identifier
  hex: utf8
}

color brand { hex = "#3366ff" }

@block("box") type Box {
  fill: &Color   // a reference, not an inlined copy
}