mirror of
https://github.com/IBM/fp-go.git
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187 lines
6.3 KiB
Go
187 lines
6.3 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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RR "github.com/IBM/fp-go/v2/internal/record"
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)
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// TraverseRecordG transforms a map by applying a function that returns an Either to each value.
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// If any value produces a Left, the entire result is that Left (short-circuits).
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// Otherwise, returns Right containing the map of all Right values.
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// The G suffix indicates support for generic map 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.TraverseRecordG[map[string]string, map[string]int](parse)(map[string]string{"a": "1", "b": "2"})
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// // result is Right(map[string]int{"a": 1, "b": 2})
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//
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//go:inline
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func TraverseRecordG[GA ~map[K]A, GB ~map[K]B, K comparable, E, A, B any](f Kleisli[E, A, B]) Kleisli[E, GA, GB] {
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return func(ga GA) Either[E, GB] {
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bs := make(GB, len(ga))
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for i, a := range ga {
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b := f(a)
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if b.isLeft {
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return Left[GB](b.l)
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}
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bs[i] = b.r
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}
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return Of[E](bs)
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}
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}
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// TraverseRecord transforms a map by applying a function that returns an Either to each value.
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// If any value produces a Left, the entire result is that Left (short-circuits).
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// Otherwise, returns Right containing the map 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.TraverseRecord[string](parse)(map[string]string{"a": "1", "b": "2"})
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// // result is Right(map[string]int{"a": 1, "b": 2})
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//
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//go:inline
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func TraverseRecord[K comparable, E, A, B any](f Kleisli[E, A, B]) Kleisli[E, map[K]A, map[K]B] {
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return TraverseRecordG[map[K]A, map[K]B](f)
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}
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// TraverseRecordWithIndexG transforms a map by applying an indexed function that returns an Either.
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// The function receives both the key and the value.
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// If any value produces a Left, the entire result is that Left (short-circuits).
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// The G suffix indicates support for generic map types.
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//
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// Example:
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//
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// validate := func(k string, v string) either.Either[error, string] {
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// if len(v) > 0 {
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// return either.Right[error](k + ":" + v)
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// }
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// return either.Left[string](fmt.Errorf("empty value for key %s", k))
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// }
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// result := either.TraverseRecordWithIndexG[map[string]string, map[string]string](validate)(map[string]string{"a": "1"})
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// // result is Right(map[string]string{"a": "a:1"})
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//
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//go:inline
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func TraverseRecordWithIndexG[GA ~map[K]A, GB ~map[K]B, K comparable, E, A, B any](f func(K, A) Either[E, B]) Kleisli[E, GA, GB] {
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return func(ga GA) Either[E, GB] {
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bs := make(GB, len(ga))
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for i, a := range ga {
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b := f(i, a)
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if b.isLeft {
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return Left[GB](b.l)
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}
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bs[i] = b.r
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}
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return Of[E](bs)
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}
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}
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// TraverseRecordWithIndex transforms a map by applying an indexed function that returns an Either.
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// The function receives both the key and the value.
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// If any value 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(k string, v string) either.Either[error, string] {
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// if len(v) > 0 {
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// return either.Right[error](k + ":" + v)
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// }
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// return either.Left[string](fmt.Errorf("empty value for key %s", k))
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// }
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// result := either.TraverseRecordWithIndex[string](validate)(map[string]string{"a": "1"})
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// // result is Right(map[string]string{"a": "a:1"})
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//
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//go:inline
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func TraverseRecordWithIndex[K comparable, E, A, B any](f func(K, A) Either[E, B]) Kleisli[E, map[K]A, map[K]B] {
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return TraverseRecordWithIndexG[map[K]A, map[K]B](f)
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}
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//go:inline
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func SequenceRecordG[GA ~map[K]A, GOA ~map[K]Either[E, A], K comparable, E, A any](ma GOA) Either[E, GA] {
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return TraverseRecordG[GOA, GA](F.Identity[Either[E, A]])(ma)
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}
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// SequenceRecord converts a map of Either values into an Either of a map.
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// If any value is Left, returns that Left (short-circuits).
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// Otherwise, returns Right containing a map of all the Right values.
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//
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// Example:
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//
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// eithers := map[string]either.Either[error, int]{
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// "a": either.Right[error](1),
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// "b": either.Right[error](2),
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// }
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// result := either.SequenceRecord(eithers)
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// // result is Right(map[string]int{"a": 1, "b": 2})
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//
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//go:inline
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func SequenceRecord[K comparable, E, A any](ma map[K]Either[E, A]) Either[E, map[K]A] {
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return SequenceRecordG[map[K]A](ma)
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}
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func upsertAtReadWrite[M ~map[K]V, K comparable, V any](r M, k K, v V) M {
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r[k] = v
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return r
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}
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// CompactRecordG discards all Left values and keeps only the Right values.
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// The G suffix indicates support for generic map types.
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//
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// Example:
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//
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// eithers := map[string]either.Either[error, int]{
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// "a": either.Right[error](1),
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// "b": either.Left[int](errors.New("error")),
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// "c": either.Right[error](3),
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// }
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// result := either.CompactRecordG[map[string]either.Either[error, int], map[string]int](eithers)
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// // result is map[string]int{"a": 1, "c": 3}
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func CompactRecordG[M1 ~map[K]Either[E, A], M2 ~map[K]A, K comparable, E, A any](m M1) M2 {
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out := make(M2)
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onLeft := F.Constant1[E](out)
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return RR.ReduceWithIndex(m, func(key K, _ M2, value Either[E, A]) M2 {
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return MonadFold(value, onLeft, func(v A) M2 {
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return upsertAtReadWrite(out, key, v)
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})
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}, out)
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}
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// CompactRecord 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 := map[string]either.Either[error, int]{
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// "a": either.Right[error](1),
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// "b": either.Left[int](errors.New("error")),
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// "c": either.Right[error](3),
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// }
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// result := either.CompactRecord(eithers)
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// // result is map[string]int{"a": 1, "c": 3}
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//
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//go:inline
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func CompactRecord[K comparable, E, A any](m map[K]Either[E, A]) map[K]A {
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return CompactRecordG[map[K]Either[E, A], map[K]A](m)
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}
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