import { Decimal } from 'decimal.js';
import { Type } from '../types/datatype';
import { Environment } from './environment';
interface ICallable {
    call(environment: Environment, argument: Type[]): Type | number | Decimal;
}
declare type FcalFunctionFmt = (environment: Environment, argument: Type[]) => Type | number | Decimal;
/**
 * IUseFunction
 * Interface for UseFunction
 */
interface IUseFunction {
    name: string;
    arity: number;
    func: FcalFunctionFmt;
}
/**
 * FcalFunction represents function in fcal
 */
declare class FcalFunction implements ICallable {
    readonly arity: number;
    readonly name: string;
    readonly function: FcalFunctionFmt;
    /**
     * Create new Fcal function
     * @param name name of the function
     * @param arity number of arguments function can expect, -1 for any number of functions
     * @param func function implementation
     */
    constructor(name: string, arity: number, func: FcalFunctionFmt);
    /**
     * call the function
     * @param {Environment} environment state of fcal
     * @param {Array<Type>} argument arguments of the function
     * @returns {Type} function result
     * @throws {FcalError} Error if function return invalid return type
     */
    call(environment: Environment, argument: Type[]): Type;
}
/**
 * List of fcal functions
 */
declare namespace FcalFunction {
    class List {
        readonly functions: Map<string, FcalFunction>;
        constructor();
        /**
         * Add new fcal function
         * @param {FcalFunction} fcalFunction
         * @throws {FcalError} Error if function name is already exists
         */
        push(ff: FcalFunction): void;
        /**
         * Call a function by its name
         * @param {string} name name of the function
         * @param {Environment} environment state of fcal
         * @param {Array<Type>} argument arguments for the function
         * @param {Type} Type result of the function
         * @throws {FcalError} Error if function is not found
         */
        call(name: string, environment: Environment, argument: Type[]): Type | number | Decimal;
        /**
         * Get function implementation by its function name
         * @param {string} name function name
         * @returns {FcalFunction | undefined} function
         */
        get(name: string): FcalFunction | undefined;
    }
}
export { FcalFunction, IUseFunction, FcalFunctionFmt };