mirror of
https://github.com/IBM/fp-go.git
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165 lines
5.5 KiB
Go
165 lines
5.5 KiB
Go
// Copyright (c) 2023 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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RA "github.com/IBM/fp-go/v2/internal/array"
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)
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// TraverseArrayG transforms an array by applying a function that returns an Either to each element.
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// If any element produces a Left, the entire result is that Left (short-circuits).
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// Otherwise, returns Right containing the array of all Right values.
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// The G suffix indicates support for generic slice types.
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//
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// Example:
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//
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// parse := func(s string) either.Either[error, int] {
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// v, err := strconv.Atoi(s)
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// return either.FromError(v, err)
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// }
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// result := either.TraverseArrayG[[]string, []int](parse)([]string{"1", "2", "3"})
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// // result is Right([]int{1, 2, 3})
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func TraverseArrayG[GA ~[]A, GB ~[]B, E, A, B any](f func(A) Either[E, B]) func(GA) Either[E, GB] {
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return RA.Traverse[GA](
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Of[E, GB],
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Map[E, GB, func(B) GB],
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Ap[GB, E, B],
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f,
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)
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}
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// TraverseArray transforms an array by applying a function that returns an Either to each element.
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// If any element produces a Left, the entire result is that Left (short-circuits).
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// Otherwise, returns Right containing the array of all Right values.
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//
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// Example:
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//
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// parse := func(s string) either.Either[error, int] {
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// v, err := strconv.Atoi(s)
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// return either.FromError(v, err)
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// }
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// result := either.TraverseArray(parse)([]string{"1", "2", "3"})
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// // result is Right([]int{1, 2, 3})
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func TraverseArray[E, A, B any](f func(A) Either[E, B]) func([]A) Either[E, []B] {
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return TraverseArrayG[[]A, []B](f)
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}
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// TraverseArrayWithIndexG transforms an array by applying an indexed function that returns an Either.
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// The function receives both the index and the element.
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// If any element produces a Left, the entire result is that Left (short-circuits).
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// The G suffix indicates support for generic slice types.
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//
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// Example:
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//
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// validate := func(i int, s string) either.Either[error, string] {
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// if len(s) > 0 {
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// return either.Right[error](fmt.Sprintf("%d:%s", i, s))
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// }
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// return either.Left[string](fmt.Errorf("empty at index %d", i))
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// }
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// result := either.TraverseArrayWithIndexG[[]string, []string](validate)([]string{"a", "b"})
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// // result is Right([]string{"0:a", "1:b"})
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func TraverseArrayWithIndexG[GA ~[]A, GB ~[]B, E, A, B any](f func(int, A) Either[E, B]) func(GA) Either[E, GB] {
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return RA.TraverseWithIndex[GA](
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Of[E, GB],
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Map[E, GB, func(B) GB],
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Ap[GB, E, B],
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f,
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)
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}
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// TraverseArrayWithIndex transforms an array by applying an indexed function that returns an Either.
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// The function receives both the index and the element.
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// If any element produces a Left, the entire result is that Left (short-circuits).
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//
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// Example:
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//
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// validate := func(i int, s string) either.Either[error, string] {
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// if len(s) > 0 {
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// return either.Right[error](fmt.Sprintf("%d:%s", i, s))
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// }
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// return either.Left[string](fmt.Errorf("empty at index %d", i))
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// }
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// result := either.TraverseArrayWithIndex(validate)([]string{"a", "b"})
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// // result is Right([]string{"0:a", "1:b"})
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func TraverseArrayWithIndex[E, A, B any](f func(int, A) Either[E, B]) func([]A) Either[E, []B] {
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return TraverseArrayWithIndexG[[]A, []B](f)
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}
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//go:inline
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func SequenceArrayG[GA ~[]A, GOA ~[]Either[E, A], E, A any](ma GOA) Either[E, GA] {
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return TraverseArrayG[GOA, GA](F.Identity[Either[E, A]])(ma)
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}
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// SequenceArray converts a homogeneous sequence of Either into an Either of sequence.
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// If any element is Left, returns that Left (short-circuits).
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// Otherwise, returns Right containing all the Right values.
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//
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// Example:
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//
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// eithers := []either.Either[error, int]{
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// either.Right[error](1),
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// either.Right[error](2),
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// either.Right[error](3),
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// }
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// result := either.SequenceArray(eithers)
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// // result is Right([]int{1, 2, 3})
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//
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//go:inline
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func SequenceArray[E, A any](ma []Either[E, A]) Either[E, []A] {
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return SequenceArrayG[[]A](ma)
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}
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// CompactArrayG discards all Left values and keeps only the Right values.
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// The G suffix indicates support for generic slice types.
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//
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// Example:
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//
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// eithers := []either.Either[error, int]{
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// either.Right[error](1),
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// either.Left[int](errors.New("error")),
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// either.Right[error](3),
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// }
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// result := either.CompactArrayG[[]either.Either[error, int], []int](eithers)
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// // result is []int{1, 3}
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//
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//go:inline
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func CompactArrayG[A1 ~[]Either[E, A], A2 ~[]A, E, A any](fa A1) A2 {
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return RA.Reduce(fa, func(out A2, value Either[E, A]) A2 {
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return MonadFold(value, F.Constant1[E](out), F.Bind1st(RA.Append[A2, A], out))
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}, make(A2, 0, len(fa)))
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}
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// CompactArray discards all Left values and keeps only the Right values.
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//
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// Example:
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//
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// eithers := []either.Either[error, int]{
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// either.Right[error](1),
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// either.Left[int](errors.New("error")),
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// either.Right[error](3),
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// }
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// result := either.CompactArray(eithers)
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// // result is []int{1, 3}
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//
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//go:inline
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func CompactArray[E, A any](fa []Either[E, A]) []A {
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return CompactArrayG[[]Either[E, A], []A](fa)
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}
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