import { NodeDefinition, StatelessGraphNode, StatelessNodeDefinition, StatelessNodeType } from '../../types/graph';
/**
 * An instance of the [[head]] node.
 * See the [[head]] documentation to find out more.
 */
export interface HeadNode extends StatelessGraphNode<'head', HeadNodeProperties> {
}
/**
 * A definition of the [[head]] node.
 * See the [[head]] documentation to find out more.
 */
export interface HeadNodeDefinition extends StatelessNodeDefinition<'head', HeadNodeProperties> {
}
export interface HeadNodeProperties {
    target: NodeDefinition;
}
/**
 * The implementation of the [[head]] node.
 * See the [[head]] documentation to learn more.
 */
export declare const HeadNodeType: StatelessNodeType<'head', HeadNodeProperties>;
/**
 * Creates a new instance of a [[head]] node, which is a type of a [[NodeDefinition]] used by the [[get]]
 * when extracting the first item from the collection.
 * It serves as a helper node that generates a [[firstItem]] transform and applies that to the target collection.
 * This node resolves to a single [[NodeDefinition]] or a [[nil]] when the collection is found to be empty.
 *
 * @example **Take first item from the collection**
 * ```js
 * import muster, { head, ref } from '@dws/muster';
 *
 * const app = muster({
 *   numbers: [1, 2, 3, 4],
 * });
 *
 * await app.resolve(head(ref('numbers')));
 * // === 1
 * ```
 * This example shows how to use the [[head]] node to extract the first item from the [[array]].
 */
export declare function head(target: NodeDefinition): HeadNodeDefinition;