export interface Semigroup<A> {
  readonly concat: (x: A, y: A) => A
}

export const semigroupAll: Semigroup<boolean> = ...

export const semigroupAny: Semigroup<boolean> = ...

export const semigroupProduct: Semigroup<number> = ...

export const semigroupString: Semigroup<string> = ...

export const semigroupSum: Semigroup<number> = ...

export const semigroupVoid: Semigroup<void> = ...

export const fold = <A>(S: Semigroup<A>) => (a: A) => (as: Array<A>): A => ...

export const getArraySemigroup = <A = never>(): Semigroup<Array<A>> => ...

export function getDictionarySemigroup<K extends string, A>(S: Semigroup<A>): Semigroup<Record<K, A>>
export function getDictionarySemigroup<A>(S: Semigroup<A>): Semigroup<{ [key: string]: A }> { ... }

export const getDualSemigroup = <A>(S: Semigroup<A>): Semigroup<A> => ...

export const getFirstSemigroup = <A = never>(): Semigroup<A> => ...

export const getFunctionSemigroup = <S>(S: Semigroup<S>) => <A = never>(): Semigroup<(a: A) => S> => ...

export const getJoinSemigroup = <A>(O: Ord<A>): Semigroup<A> => ...

export const getLastSemigroup = <A = never>(): Semigroup<A> => ...

export const getMeetSemigroup = <A>(O: Ord<A>): Semigroup<A> => ...

export const getObjectSemigroup = <A extends object = never>(): Semigroup<A> => ...

import { getObjectSemigroup } from 'fp-ts/lib/Semigroup'

interface Person {
  name: string
  age: number
}

const S = getObjectSemigroup<Person>()
assert.deepStrictEqual(S.concat({ name: 'name', age: 23 }, { name: 'name', age: 24 }), { name: 'name', age: 24 })

export const getProductSemigroup = <A, B>(SA: Semigroup<A>, SB: Semigroup<B>): Semigroup<[A, B]> => ...

export const getRecordSemigroup = <O extends { [key: string]: any }>(
  semigroups: { [K in keyof O]: Semigroup<O[K]> }
): Semigroup<O> => ...

export const getStructSemigroup = <O extends { [key: string]: any }>(
  semigroups: { [K in keyof O]: Semigroup<O[K]> }
): Semigroup<O> => ...

export const getTupleSemigroup = <A, B>(SA: Semigroup<A>, SB: Semigroup<B>): Semigroup<[A, B]> => ...