fix: add ReaderIOEither sample

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

samples/getting-started-with-fp-ts/reader/example1/reader_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package reader implements the example in [https://dev.to/gcanti/getting-started-with-fp-ts-reader-1ie5]
+// Package example1 implements the first example in [https://dev.to/gcanti/getting-started-with-fp-ts-reader-1ie5]
 package example1
 
 import (

samples/getting-started-with-fp-ts/reader/example2/reader_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package reader implements the example in [https://dev.to/gcanti/getting-started-with-fp-ts-reader-1ie5]
+// Package example2 implements the second example in [https://dev.to/gcanti/getting-started-with-fp-ts-reader-1ie5]
 package example2
 
 import (

samples/readerioeither/example1/reader_test.go

@@ -0,0 +1,89 @@
+// 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 example1
+
+import (
+	"os"
+
+	B "github.com/IBM/fp-go/bytes"
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	I "github.com/IBM/fp-go/identity"
+	IOE "github.com/IBM/fp-go/ioeither"
+	J "github.com/IBM/fp-go/json"
+	RIOE "github.com/IBM/fp-go/readerioeither"
+)
+
+type (
+	WriterType = func([]byte) IOE.IOEither[error, []byte]
+
+	Dependencies struct {
+		Writer WriterType
+	}
+)
+
+func getWriter(deps *Dependencies) WriterType {
+	return deps.Writer
+}
+
+// SerializeToWriter marshals the input to JSON and persists the result via the [Writer] passed in via the [*Dependencies]
+func SerializeToWriter[A any](data A) RIOE.ReaderIOEither[*Dependencies, error, []byte] {
+	return F.Pipe1(
+		RIOE.Ask[*Dependencies, error](),
+		RIOE.ChainIOEitherK[*Dependencies](F.Flow2(
+			getWriter,
+			F.Pipe2(
+				data,
+				J.Marshal[A],
+				E.Fold(F.Flow2(
+					IOE.Left[[]byte, error],
+					F.Constant1[WriterType, IOE.IOEither[error, []byte]],
+				), I.Ap[IOE.IOEither[error, []byte], []byte]),
+			),
+		)),
+	)
+}
+
+func ExampleReaderIOEither() {
+
+	// writeToStdOut implements a writer to stdout
+	writeToStdOut := func(data []byte) IOE.IOEither[error, []byte] {
+		return IOE.TryCatchError(func() ([]byte, error) {
+			_, err := os.Stdout.Write(data)
+			return data, err
+		})
+	}
+
+	deps := Dependencies{
+		Writer: writeToStdOut,
+	}
+
+	data := map[string]string{
+		"a": "b",
+		"c": "d",
+	}
+
+	// writeData will persist to a configurable target
+	writeData := F.Pipe1(
+		SerializeToWriter(data),
+		RIOE.Map[*Dependencies, error](B.ToString),
+	)
+
+	_ = writeData(&deps)()
+
+	// Output:
+	// {"a":"b","c":"d"}
+}