/**
 * Expression Lowering
 *
 * Transforms MEL Canonical IR (8 kinds) to Core Runtime IR (30+ kinds).
 *
 * @see SPEC v0.4.0 §17
 */
import type { ExprNode as CoreExprNode } from "@manifesto-ai/core";
import type { ExprLoweringContext } from "./context.js";
/**
 * MEL primitive value.
 */
export type MelPrimitive = null | boolean | number | string;
/**
 * MEL path segment.
 */
export type MelPathSegment = {
    kind: "prop";
    name: string;
};
/**
 * MEL path node array.
 */
export type MelPathNode = MelPathSegment[];
/**
 * MEL system path as segment array.
 */
export type MelSystemPath = string[];
/**
 * MEL object field.
 */
export type MelObjField = {
    key: string;
    value: MelExprNode;
};
/**
 * MEL Canonical IR (8 kinds).
 *
 * @see SPEC v0.4.0 §17.1.1
 */
export type MelExprNode = {
    kind: "lit";
    value: MelPrimitive;
} | {
    kind: "var";
    name: "item";
} | {
    kind: "sys";
    path: MelSystemPath;
} | {
    kind: "get";
    base?: MelExprNode;
    path: MelPathNode;
} | {
    kind: "field";
    object: MelExprNode;
    property: string;
} | {
    kind: "call";
    fn: string;
    args: MelExprNode[];
} | {
    kind: "obj";
    fields: MelObjField[];
} | {
    kind: "arr";
    elements: MelExprNode[];
};
/**
 * Lower MEL expression to Core expression.
 *
 * @param input - MEL canonical IR expression
 * @param ctx - Lowering context
 * @returns Core runtime IR expression
 * @throws LoweringError if expression cannot be lowered
 *
 * @see SPEC v0.4.0 §17.3
 */
export declare function lowerExprNode(input: MelExprNode, ctx: ExprLoweringContext): CoreExprNode;