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fp-go/writer/writer_test.go
Dr. Carsten Leue 01786a054b fix: refactor Writer monad
Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>
2024-02-13 10:44:57 +01:00

46 lines
1.1 KiB
Go

// Copyright (c) 2023 IBM Corp.
// All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package writer
import (
"fmt"
A "github.com/IBM/fp-go/array"
F "github.com/IBM/fp-go/function"
P "github.com/IBM/fp-go/pair"
)
func doubleAndLog(data int) Writer[[]string, int] {
return func() P.Pair[int, []string] {
result := data * 2
return P.MakePair(result, A.Of(fmt.Sprintf("Doubled %d -> %d", data, result)))
}
}
func ExampleWriter_logging() {
res := F.Pipe3(
Of[int](monoid, 10),
Chain(sg, doubleAndLog),
Chain(sg, doubleAndLog),
Execute[[]string, int],
)
fmt.Println(res)
// Output: [Doubled 10 -> 20 Doubled 20 -> 40]
}