Function compose

packages/effect/src/Optic.ts:383–399

(a: Node, b: Node)

}

function compose(a: Node, b: Node): Node {
  if (a.length === 0) return b
  if (b.length === 0) return a
  const nodes = a.slice()
  for (let i = 0; i < b.length; i++) {
    const node = b[i]
    const last = nodes[nodes.length - 1]
    if (last._tag === "PathNode" && node._tag === "PathNode") {
      nodes[nodes.length - 1] = new PathNode([...last.path, ...node.path])
    } else if (last._tag === "CheckNode" && node._tag === "CheckNode") {
      nodes[nodes.length - 1] = new CheckNode<any>([...last.checks, ...node.checks])
    } else {
      nodes.push(node)
    }
  }
  return nodes
}

type ForbidUnion<A, Message extends string> = IsUnion<A> extends true ? [Message] : []