fix: add missing alt methods and semigroup

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

ioeither/monoid_test.go

@@ -0,0 +1,42 @@
+//   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 ioeither
+
+import (
+	"fmt"
+	"testing"
+
+	E "github.com/IBM/fp-go/either"
+	S "github.com/IBM/fp-go/string"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestApplicativeMonoid(t *testing.T) {
+	m := ApplicativeMonoid[error](S.Monoid)
+
+	// good cases
+	assert.Equal(t, E.Of[error]("ab"), m.Concat(Of[error]("a"), Of[error]("b"))())
+	assert.Equal(t, E.Of[error]("a"), m.Concat(Of[error]("a"), m.Empty())())
+	assert.Equal(t, E.Of[error]("b"), m.Concat(m.Empty(), Of[error]("b"))())
+
+	// bad cases
+	e1 := fmt.Errorf("e1")
+	e2 := fmt.Errorf("e1")
+
+	assert.Equal(t, E.Left[string](e1), m.Concat(Left[string](e1), Of[error]("b"))())
+	assert.Equal(t, E.Left[string](e1), m.Concat(Left[string](e1), Left[string](e2))())
+	assert.Equal(t, E.Left[string](e2), m.Concat(Of[error]("a"), Left[string](e2))())
+}