fp-go/v2/iterator/stateless/generic/monad.go

// Copyright (c) 2024 - 2025 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 generic

import (
	"github.com/IBM/fp-go/v2/internal/monad"
	O "github.com/IBM/fp-go/v2/option"
	P "github.com/IBM/fp-go/v2/pair"
)

type iteratorMonad[A, B any, GA ~func() O.Option[P.Pair[GA, A]], GB ~func() O.Option[P.Pair[GB, B]], GAB ~func() O.Option[P.Pair[GAB, func(A) B]]] struct{}

func (o *iteratorMonad[A, B, GA, GB, GAB]) Of(a A) GA {
	return Of[GA](a)
}

func (o *iteratorMonad[A, B, GA, GB, GAB]) Map(f func(A) B) func(GA) GB {
	return Map[GB, GA](f)
}

func (o *iteratorMonad[A, B, GA, GB, GAB]) Chain(f func(A) GB) func(GA) GB {
	return Chain[GB, GA](f)
}

func (o *iteratorMonad[A, B, GA, GB, GAB]) Ap(fa GA) func(GAB) GB {
	return Ap[GAB, GB](fa)
}

// Monad implements the monadic operations for iterators
func Monad[A, B any, GA ~func() O.Option[P.Pair[GA, A]], GB ~func() O.Option[P.Pair[GB, B]], GAB ~func() O.Option[P.Pair[GAB, func(A) B]]]() monad.Monad[A, B, GA, GB, GAB] {
	return &iteratorMonad[A, B, GA, GB, GAB]{}
}