import { EastFunction, GetFieldFunction, StructFunction } from '../functions';
import { EastType, StructType } from '../types';
import { Expression, ExpressionTypeOf } from './core';
/**
 * Construct a struct from an expressions for each field.
 *
 * @param fields a record of {@link Expression}s defining the struct
 *
 * @category Expression
 * @see {@link GetField}
 *
 * @example
 * ```typescript
 * // ...
 * // Create an aggregate struct with product data
 * ProductData: Struct({
 *     Id: Variable("ProductId", StringType),
 *     Name: Variable("ProductName", StringType),
 *     UnitPrice: Variable("ProductPrice", FloatType),
 *     StockLevel: Variable("ProductStockLevel", IntegerType),
 *     StockTakeDate: Variable("ProductStockTakeDate", DateTimeType),
 * }),
 * // ...
 * ```
 */
export declare function Struct<T extends Record<string, Expression<EastType>>>(fields: T): StructFunction<{
    type: "Struct";
    value: {
        [K in keyof T]: ExpressionTypeOf<T[K]>;
    };
}>;
/**
 * Fetch the value of one of a struct's fields.
 *
 * @param struct the {@link Expression} for the input struct
 * @param field the name of field to fetch
 *
 * @category Expression
 * @see {@link Struct}
 *
 * @example
 * ```typescript
 * // ...
 * // Get the name of the product from the product data
 * ProductName: GetField(
 *     Variable(product_data, StructType({
 *         Id: StringType,
 *         Name: StringType,
 *         UnitPrice: FloatType,
 *         StockLevel: IntegerType,
 *         StockTakeDate: DateTimeType,
 *     }),
 *     "Name"
 * ),
 * // ...
 * ```
 */
export declare function GetField<T extends StructType, K extends keyof T["value"]>(struct: EastFunction<T>, field: K): GetFieldFunction<T["value"][K]>;