Semigroup overview

Added in v0.24.0

Table of contents

• combinators
  • array
  • struct
  • tuple
• constructors
  • constant
  • make
  • max
  • min
• instances
  • Invariant
  • Product
  • SemiProduct
  • first
  • last
• type class
  • Semigroup (interface)
• type lambdas
  • SemigroupTypeLambda (interface)
• utils
  • imap
  • intercalate
  • reverse

combinators

array

Given a type A, this function creates and returns a Semigroup for ReadonlyArray<A>. The returned Semigroup combines two arrays by concatenating them.

Signature

export declare const array: <A>() => Semigroup<ReadonlyArray<A>>

Added in v0.24.0

struct

This function creates and returns a new Semigroup for a struct of values based on the given Semigroups for each property in the struct. The returned Semigroup combines two structs of the same type by applying the corresponding Semigroup passed as arguments to each property in the struct.

It is useful when you need to combine two structs of the same type and you have a specific way of combining each property of the struct.

Signature

export declare const struct: <R extends { readonly [x: string]: Semigroup<any> }>(
  fields: R
) => Semigroup<{ readonly [K in keyof R]: [R[K]] extends [Semigroup<infer A>] ? A : never }>

Added in v0.24.0

tuple

Similar to Promise.all but operates on Semigroups.

[Semigroup<A>, Semigroup<B>, ...] -> Semigroup<[A, B, ...]>

This function creates and returns a new Semigroup for a tuple of values based on the given Semigroups for each element in the tuple. The returned Semigroup combines two tuples of the same type by applying the corresponding Semigroup passed as arguments to each element in the tuple.

It is useful when you need to combine two tuples of the same type and you have a specific way of combining each element of the tuple.

Signature

export declare const tuple: <T extends ReadonlyArray<Semigroup<any>>>(
  ...elements: T
) => Semigroup<{ readonly [I in keyof T]: [T[I]] extends [Semigroup<infer A>] ? A : never }>

Added in v0.24.0

constructors

constant

Signature

export declare const constant: <A>(a: A) => Semigroup<A>

Added in v0.24.0

make

Signature

export declare const make: <A>(
  combine: Semigroup<A>["combine"],
  combineMany?: Semigroup<A>["combineMany"]
) => Semigroup<A>

Added in v0.24.0

max

Semigroup that returns last maximum of elements.

Signature

export declare const max: <A>(O: Order<A>) => Semigroup<A>

Added in v0.24.0

min

Semigroup that returns last minimum of elements.

Signature

export declare const min: <A>(O: Order<A>) => Semigroup<A>

Added in v0.24.0

instances

Invariant

Signature

export declare const Invariant: invariant.Invariant<SemigroupTypeLambda>

Added in v0.24.0

Product

Signature

export declare const Product: product_.Product<SemigroupTypeLambda>

Added in v0.24.0

SemiProduct

Signature

export declare const SemiProduct: semiProduct.SemiProduct<SemigroupTypeLambda>

Added in v0.24.0

first

Always return the first argument.

Signature

export declare const first: <A = never>() => Semigroup<A>

Added in v0.24.0

last

Always return the last argument.

Signature

export declare const last: <A = never>() => Semigroup<A>

Added in v0.24.0

type class

Semigroup (interface)

Signature

export interface Semigroup<A> {
  readonly combine: (self: A, that: A) => A
  readonly combineMany: (self: A, collection: Iterable<A>) => A
}

Added in v0.24.0

type lambdas

SemigroupTypeLambda (interface)

Signature

export interface SemigroupTypeLambda extends TypeLambda {
  readonly type: Semigroup<this["Target"]>
}

Added in v0.24.0

utils

imap

Signature

export declare const imap: {
  <A, B>(to: (a: A) => B, from: (b: B) => A): (self: Semigroup<A>) => Semigroup<B>
  <A, B>(self: Semigroup<A>, to: (a: A) => B, from: (b: B) => A): Semigroup<B>
}

Added in v0.24.0

intercalate

The intercalate API returns a function that takes a Semigroup instance and a separator value, and returns a new Semigroup instance that combines values with the given separator.

This API is useful when you want to combine values with a specific separator. For example, when you want to concatenate an array of strings with a separator string in between.

It is interesting to note that there is no equivalent API in the Monoid module. This is because the value empty, which is required for the Monoid interface, cannot exist.

Signature

export declare const intercalate: {
  <A>(separator: A): (S: Semigroup<A>) => Semigroup<A>
  <A>(S: Semigroup<A>, separator: A): Semigroup<A>
}

Added in v0.24.0

reverse

The dual of a Semigroup, obtained by flipping the arguments of combine.

Signature

export declare const reverse: <A>(S: Semigroup<A>) => Semigroup<A>

Added in v0.24.0