/**
 * **This module is experimental**
 *
 * Experimental features are published in order to get early feedback from the community, see these tracking
 * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
 *
 * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
 *
 * @since 2.2.7
 */
import { Semigroup } from 'fp-ts/lib/Semigroup'
/**
 * @category model
 * @since 2.2.7
 */
export interface Of<A> {
  readonly _tag: 'Of'
  readonly value: A
}
/**
 * @category model
 * @since 2.2.7
 */
export interface Concat<A> {
  readonly _tag: 'Concat'
  readonly left: FreeSemigroup<A>
  readonly right: FreeSemigroup<A>
}
/**
 * @category model
 * @since 2.2.7
 */
export declare type FreeSemigroup<A> = Of<A> | Concat<A>
/**
 * @category constructors
 * @since 2.2.7
 */
export declare const of: <A>(a: A) => FreeSemigroup<A>
/**
 * @category constructors
 * @since 2.2.7
 */
export declare const concat: <A>(left: FreeSemigroup<A>, right: FreeSemigroup<A>) => FreeSemigroup<A>
/**
 * @category destructors
 * @since 2.2.7
 */
export declare const fold: <A, R>(
  onOf: (value: A) => R,
  onConcat: (left: FreeSemigroup<A>, right: FreeSemigroup<A>) => R
) => (f: FreeSemigroup<A>) => R
/**
 * @category instances
 * @since 2.2.7
 */
export declare function getSemigroup<A = never>(): Semigroup<FreeSemigroup<A>>