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69 lines
2.6 KiB
Go
69 lines
2.6 KiB
Go
// Copyright (c) 2023 - 2025 IBM Corp.
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// All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package either
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import (
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F "github.com/IBM/fp-go/v2/function"
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)
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// Traverse converts an Either of some higher kinded type into the higher kinded type of an Either.
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// This is a generic traversal operation that works with any applicative functor.
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//
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// Parameters:
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// - mof: Lifts an Either into the target higher-kinded type
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// - mmap: Maps over the target higher-kinded type
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//
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// Example (conceptual - requires understanding of higher-kinded types):
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//
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// // Traverse an Either[error, Option[int]] to Option[Either[error, int]]
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// result := either.Traverse[int, error, int, option.Option[int], option.Option[either.Either[error, int]]](
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// option.Of[either.Either[error, int]],
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// option.Map[int, either.Either[error, int]],
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// )(f)(eitherOfOption)
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func Traverse[A, E, B, HKTB, HKTRB any](
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mof func(Either[E, B]) HKTRB,
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mmap func(Kleisli[E, B, B]) func(HKTB) HKTRB,
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) func(func(A) HKTB) func(Either[E, A]) HKTRB {
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left := F.Flow2(Left[B, E], mof)
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right := mmap(Right[E, B])
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return func(f func(A) HKTB) func(Either[E, A]) HKTRB {
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return Fold(left, F.Flow2(f, right))
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}
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}
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// Sequence converts an Either of some higher kinded type into the higher kinded type of an Either.
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// This is the identity version of Traverse - it doesn't transform the values, just swaps the type constructors.
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//
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// Parameters:
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// - mof: Lifts an Either into the target higher-kinded type
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// - mmap: Maps over the target higher-kinded type
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//
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// Example (conceptual - requires understanding of higher-kinded types):
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//
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// // Sequence an Either[error, Option[int]] to Option[Either[error, int]]
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// result := either.Sequence[error, int, option.Option[int], option.Option[either.Either[error, int]]](
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// option.Of[either.Either[error, int]],
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// option.Map[int, either.Either[error, int]],
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// )(eitherOfOption)
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func Sequence[E, A, HKTA, HKTRA any](
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mof func(Either[E, A]) HKTRA,
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mmap func(Kleisli[E, A, A]) func(HKTA) HKTRA,
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) func(Either[E, HKTA]) HKTRA {
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return Fold(F.Flow2(Left[A, E], mof), mmap(Right[E, A]))
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}
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