/**
 * Type for signifying one-variable type predicates
 */
export type TypePredicate<Type = any> = (x?: any) => x is Type;
/**
 * A type of all the items `x`, such that `!x` is truthy
 */
export type Falsy = false | 0 | "" | null | undefined;
/**
 * Returns whether a given `x` is a number primitive
 */
export declare const isNumber: (x: any) => x is number;
/**
 * Returns whether `x` is a function
 */
export declare const isFunction: (x: any) => x is Function;
/**
 * Returns whether `x` is a string primitive
 */
export declare const isString: (x: any) => x is string;
/**
 * Returns whether `x` is a boolean primitive
 */
export declare const isBoolean: (x: any) => x is boolean;
/**
 * Returns whether `x` is a symbol primitive
 */
export declare const isSymbol: (x: any) => x is symbol;
/**
 * Returns whether `x` is an object
 */
export declare const isObject: <Type extends object = object>(x: any) => x is Type;
/**
 * Returns whether `x` is `null`
 */
export declare const isNull: (x: any) => x is null;
/**
 * Returns whether `x` is `undefined`
 */
export declare const isUndefined: (x: any) => x is undefined;
/**
 * Returns whether `x == null`
 */
export declare const isNullary: (x: any) => x is undefined | null;
/**
 * Returns `typeof x`
 */
export declare const typeOf: (x: any) => "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function";
/**
 * Returns whether `x` is an `Array`
 */
export declare const isArray: <Type = any>(x: any) => x is Type[];
/**
 * Returns whether `x` is a `Set`
 */
export declare const isSet: <Type = any>(x: any) => x is Set<Type>;
/**
 * Returns whether `x` is a `Map`
 */
export declare const isMap: <KType = any, VType = any>(x: any) => x is Map<KType, VType>;
/**
 * Returns a bool indicating whether it is possible to call `Number(x)` without:
 *
 * 1. getting `NaN`
 * 2. getting an error (this happens if `x` is a symbol)
 * 3. `x` being an empty string
 */
export declare function isNumberConvertible(x: any): boolean;
/**
 * Returns whether `x` is a truthy value
 */
export declare const isTruthy: (x: any) => boolean;
/**
 * Checks whether the given `x` is `Falsy`
 */
export declare const isFalsy: (x: any) => x is Falsy;
/**
 * Returns either `x` if it's a non-`null` object, or `false`, if it isn't
 */
export declare const isStruct: (x: any) => false | object;