mirror of
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185 lines
6.5 KiB
Go
185 lines
6.5 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 result
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// TraverseArrayG transforms an array by applying a function that returns a Result (value, error) to each element.
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// It processes elements from left to right, applying the function to each.
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// If any element produces an error, the entire operation short-circuits and returns that error.
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// Otherwise, it returns a successful result containing the array of all transformed values.
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//
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// The G suffix indicates support for generic slice types (e.g., custom slice types based on []T).
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//
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// Type Parameters:
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// - GA: Source slice type (must be based on []A)
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// - GB: Target slice type (must be based on []B)
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// - A: Source element type
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// - B: Target element type
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//
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// Parameters:
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// - f: A Kleisli arrow (A) -> (B, error) that transforms each element
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//
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// Returns:
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// - A Kleisli arrow (GA) -> (GB, error) that transforms the entire array
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//
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// Behavior:
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// - Short-circuits on the first error encountered
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// - Preserves the order of elements
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// - Returns an empty slice for empty input
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//
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// Example - Parse strings to integers:
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//
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// parse := func(s string) (int, error) {
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// return strconv.Atoi(s)
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// }
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// result := result.TraverseArrayG[[]string, []int](parse)([]string{"1", "2", "3"})
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// // result is ([]int{1, 2, 3}, nil)
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//
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// Example - Short-circuit on error:
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//
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// result := result.TraverseArrayG[[]string, []int](parse)([]string{"1", "bad", "3"})
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// // result is ([]int(nil), error) - stops at "bad"
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func TraverseArrayG[GA ~[]A, GB ~[]B, A, B any](f Kleisli[A, B]) Kleisli[GA, GB] {
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return func(ga GA) (GB, error) {
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bs := make(GB, len(ga))
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for i, a := range ga {
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b, err := f(a)
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if err != nil {
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return Left[GB](err)
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}
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bs[i] = b
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}
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return Of(bs)
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}
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}
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// TraverseArray transforms an array by applying a function that returns a Result (value, error) to each element.
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// It processes elements from left to right, applying the function to each.
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// If any element produces an error, the entire operation short-circuits and returns that error.
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// Otherwise, it returns a successful result containing the array of all transformed values.
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//
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// This is a convenience wrapper around [TraverseArrayG] for standard slice types.
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//
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// Type Parameters:
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// - A: Source element type
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// - B: Target element type
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//
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// Parameters:
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// - f: A Kleisli arrow (A) -> (B, error) that transforms each element
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//
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// Returns:
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// - A Kleisli arrow ([]A) -> ([]B, error) that transforms the entire array
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//
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// Example - Validate and transform:
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//
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// validate := func(s string) (int, error) {
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// n, err := strconv.Atoi(s)
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// if err != nil {
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// return 0, err
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// }
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// if n < 0 {
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// return 0, errors.New("negative number")
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// }
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// return n * 2, nil
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// }
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// result := result.TraverseArray(validate)([]string{"1", "2", "3"})
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// // result is ([]int{2, 4, 6}, nil)
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//
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//go:inline
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func TraverseArray[A, B any](f Kleisli[A, B]) Kleisli[[]A, []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 a Result (value, error).
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// The function receives both the zero-based index and the element for each iteration.
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// If any element produces an error, the entire operation short-circuits and returns that error.
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// Otherwise, it returns a successful result containing the array of all transformed values.
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//
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// The G suffix indicates support for generic slice types (e.g., custom slice types based on []T).
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//
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// Type Parameters:
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// - GA: Source slice type (must be based on []A)
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// - GB: Target slice type (must be based on []B)
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// - A: Source element type
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// - B: Target element type
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//
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// Parameters:
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// - f: An indexed function (int, A) -> (B, error) that transforms each element
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//
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// Returns:
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// - A Kleisli arrow (GA) -> (GB, error) that transforms the entire array
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//
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// Behavior:
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// - Processes elements from left to right with their indices (0, 1, 2, ...)
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// - Short-circuits on the first error encountered
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// - Preserves the order of elements
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//
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// Example - Annotate with index:
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//
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// annotate := func(i int, s string) (string, error) {
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// if len(s) == 0 {
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// return "", fmt.Errorf("empty string at index %d", i)
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// }
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// return fmt.Sprintf("[%d]=%s", i, s), nil
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// }
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// result := result.TraverseArrayWithIndexG[[]string, []string](annotate)([]string{"a", "b", "c"})
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// // result is ([]string{"[0]=a", "[1]=b", "[2]=c"}, nil)
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func TraverseArrayWithIndexG[GA ~[]A, GB ~[]B, A, B any](f func(int, A) (B, error)) Kleisli[GA, GB] {
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return func(ga GA) (GB, error) {
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bs := make(GB, len(ga))
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for i, a := range ga {
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b, err := f(i, a)
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if err != nil {
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return Left[GB](err)
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}
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bs[i] = b
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}
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return Of(bs)
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}
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}
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// TraverseArrayWithIndex transforms an array by applying an indexed function that returns a Result (value, error).
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// The function receives both the zero-based index and the element for each iteration.
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// If any element produces an error, the entire operation short-circuits and returns that error.
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// Otherwise, it returns a successful result containing the array of all transformed values.
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//
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// This is a convenience wrapper around [TraverseArrayWithIndexG] for standard slice types.
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//
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// Type Parameters:
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// - A: Source element type
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// - B: Target element type
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//
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// Parameters:
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// - f: An indexed function (int, A) -> (B, error) that transforms each element
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//
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// Returns:
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// - A Kleisli arrow ([]A) -> ([]B, error) that transforms the entire array
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//
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// Example - Validate with position info:
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//
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// check := func(i int, s string) (string, error) {
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// if len(s) == 0 {
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// return "", fmt.Errorf("empty value at position %d", i)
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// }
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// return strings.ToUpper(s), nil
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// }
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// result := result.TraverseArrayWithIndex(check)([]string{"a", "b", "c"})
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// // result is ([]string{"A", "B", "C"}, nil)
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//
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//go:inline
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func TraverseArrayWithIndex[A, B any](f func(int, A) (B, error)) Kleisli[[]A, []B] {
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return TraverseArrayWithIndexG[[]A, []B](f)
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}
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