Semigroup API Reference

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

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

tuple

Since v0.24.0

Similar to Promise.all but operates on Semigroups.

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

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

Example

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

Constructors

constant

Since v0.24.0

Signature

declare function constant<A>(a: A): Semigroup<A>

make

Since v0.24.0

The combineMany parameter is optional and defaults to a standard implementation. You can provide a custom implementation when performance optimizations are possible.

Signature

declare function make<A>(combine: (self: A, that: A) => A, combineMany: (self: A, collection: Iterable<A>) => A): Semigroup<A>

max

Since v0.24.0

Semigroup that returns last maximum of elements.

Signature

declare function max<A>(O: Order<A>): Semigroup<A>

min

Since v0.24.0

Semigroup that returns last minimum of elements.

Signature

declare function min<A>(O: Order<A>): Semigroup<A>

Instances

first

Since v0.24.0

Always return the first argument.

Signature

declare function first<A = never>(): Semigroup<A>

Invariant

Since v0.24.0

Signature

declare const Invariant: invariant.Invariant<SemigroupTypeLambda>

last

Since v0.24.0

Always return the last argument.

Signature

declare function last<A = never>(): Semigroup<A>

Product

Since v0.24.0

Signature

declare const Product: product_.Product<SemigroupTypeLambda>

SemiProduct

Since v0.24.0

Signature

declare const SemiProduct: semiProduct.SemiProduct<SemigroupTypeLambda>

Other

imap

Since v0.24.0

Signature

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>;
}

intercalate

Since v0.24.0

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

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

reverse

Since v0.24.0

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

Signature

declare function reverse<A>(S: Semigroup<A>): Semigroup<A>

Type Class

Semigroup

interface

Since v0.24.0

Signature

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

Type Lambdas

SemigroupTypeLambda

interface

Since v0.24.0

Signature

interface SemigroupTypeLambda extends TypeLambda {
  readonly type: Semigroup<unknown>;
}