mirror of
https://github.com/IBM/fp-go.git
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115 lines
3.2 KiB
Go
115 lines
3.2 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 readerresult
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import (
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"context"
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"errors"
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"fmt"
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RES "github.com/IBM/fp-go/v2/result"
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)
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// ExampleFromEither demonstrates lifting a Result (Either) into a
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// The resulting ReaderResult ignores the context and returns the Result value.
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func ExampleFromEither() {
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res := RES.Of(42)
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rr := FromEither(res)
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value, err := rr(context.Background())
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fmt.Println(value, err)
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// Output:
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// 42 <nil>
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}
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// ExampleFromResult demonstrates creating a ReaderResult from a Go-style (value, error) tuple.
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// This is useful for converting standard Go error handling into the ReaderResult monad.
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func ExampleFromResult() {
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rr := FromResult(42, nil)
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value, err := rr(context.Background())
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fmt.Println(value, err)
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// Output:
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// 42 <nil>
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}
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// ExampleFromResult_error demonstrates creating a ReaderResult from an error case.
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// The resulting ReaderResult will propagate the error when executed.
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func ExampleFromResult_error() {
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rr := FromResult(0, errors.New("failed"))
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value, err := rr(context.Background())
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fmt.Println(value, err != nil)
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// Output:
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// 0 true
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}
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// ExampleLeft demonstrates creating a ReaderResult that always fails with an error.
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// This is the error constructor for ReaderResult, analogous to Either's Left.
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func ExampleLeft() {
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rr := Left[int](errors.New("failed"))
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value, err := rr(context.Background())
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fmt.Println(value, err != nil)
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// Output:
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// 0 true
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}
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// ExampleRight demonstrates creating a ReaderResult that always succeeds with a value.
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// This is the success constructor for ReaderResult, analogous to Either's Right.
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func ExampleRight() {
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rr := Right(42)
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value, err := rr(context.Background())
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fmt.Println(value, err)
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// Output:
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// 42 <nil>
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}
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// ExampleOf demonstrates the monadic return/pure operation for
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// It creates a ReaderResult that always succeeds with the given value.
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func ExampleOf() {
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rr := Of(42)
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value, err := rr(context.Background())
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fmt.Println(value, err)
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// Output:
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// 42 <nil>
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}
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// ExampleAsk demonstrates getting the context.Context environment.
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// This returns a ReaderResult that provides access to the context itself.
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func ExampleAsk() {
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rr := Ask()
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ctx := context.Background()
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value, err := rr(ctx)
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fmt.Println(value == ctx, err)
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// Output:
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// true <nil>
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}
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// ExampleAsks demonstrates extracting a value from the context using a function.
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// This is useful for accessing configuration or other data stored in the context.
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func ExampleAsks() {
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type Config struct {
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Port int
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}
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getPort := Asks(func(ctx context.Context) int {
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// In real code, extract config from context
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return 8080
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})
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value, err := getPort(context.Background())
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fmt.Println(value, err)
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// Output:
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// 8080 <nil>
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}
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