fp-go/tuple/tuple.go

// Copyright (c) 2023 IBM Corp.
// All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package tuple contains type definitions and functions for data structures for tuples of heterogenous types. For homogeneous types
// consider to use arrays for simplicity
package tuple

func First[T1, T2 any](t Tuple2[T1, T2]) T1 {
	return t.F1
}

func Second[T1, T2 any](t Tuple2[T1, T2]) T2 {
	return t.F2
}

func Swap[T1, T2 any](t Tuple2[T1, T2]) Tuple2[T2, T1] {
	return MakeTuple2(t.F2, t.F1)
}

func Of[T1, T2 any](e T2) func(T1) Tuple2[T1, T2] {
	return func(t T1) Tuple2[T1, T2] {
		return MakeTuple2(t, e)
	}
}

func BiMap[E, G, A, B any](mapSnd func(E) G, mapFst func(A) B) func(Tuple2[A, E]) Tuple2[B, G] {
	return func(t Tuple2[A, E]) Tuple2[B, G] {
		return MakeTuple2(mapFst(First(t)), mapSnd(Second(t)))
	}
}

// Ap implements the applicative for a tuple carrying the function in its first parameter and the value in its second
func Ap[A, B any](t Tuple2[func(A) B, A]) B {
	return t.F1(t.F2)
}