Add presentation to sample section (#76)

* doc: add presentation

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

* fix: add some more examples

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

* doc: update presentation

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

* fix: update presentation

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

* fix: add presentation and samples

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

* fix: benchmarks

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

* fix: upload presentation

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

* doc: add presentation

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

* doc: add link to video

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

---------

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

samples/presentation/examples/example_immutability_test.go

@@ -0,0 +1,156 @@
+// 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 examples
+
+import (
+	"fmt"
+	"strings"
+
+	F "github.com/IBM/fp-go/function"
+	N "github.com/IBM/fp-go/number"
+	L "github.com/IBM/fp-go/optics/lens"
+)
+
+type Person struct {
+	name string
+	age  int
+}
+
+func (p Person) GetName() string {
+	return p.name
+}
+
+func (p Person) GetAge() int {
+	return p.age
+}
+
+func (p Person) SetName(name string) Person {
+	p.name = name
+	return p
+}
+
+func (p Person) SetAge(age int) Person {
+	p.age = age
+	return p
+}
+
+type Address struct {
+	city string
+}
+
+func (a Address) GetCity() string {
+	return a.city
+}
+
+func (a Address) SetCity(city string) Address {
+	a.city = city
+	return a
+}
+
+type Client struct {
+	person  Person
+	address Address
+}
+
+func (c Client) GetPerson() Person {
+	return c.person
+}
+
+func (c Client) SetPerson(person Person) Client {
+	c.person = person
+	return c
+}
+
+func (c Client) GetAddress() Address {
+	return c.address
+}
+
+func (c Client) SetAddress(address Address) Client {
+	c.address = address
+	return c
+}
+
+func MakePerson(name string, age int) Person {
+	return Person{name, age}
+}
+
+func MakeClient(city string, name string, age int) Client {
+	return Client{person: Person{name, age}, address: Address{city}}
+}
+
+func Example_immutability_struct() {
+	p1 := MakePerson("Carsten", 53)
+
+	// func(int) func(Person) Person
+	setAge := F.Curry2(F.Swap(Person.SetAge))
+
+	p2 := F.Pipe1(
+		p1,
+		setAge(54),
+	)
+
+	fmt.Println(p1)
+	fmt.Println(p2)
+
+	// Output:
+	// {Carsten 53}
+	// {Carsten 54}
+}
+
+func Example_immutability_optics() {
+
+	// Lens[Person, int]
+	ageLens := L.MakeLens(Person.GetAge, Person.SetAge)
+	// func(Person) Person
+	incAge := L.Modify[Person](N.Inc[int])(ageLens)
+
+	p1 := MakePerson("Carsten", 53)
+	p2 := incAge(p1)
+
+	fmt.Println(p1)
+	fmt.Println(p2)
+
+	// Output:
+	// {Carsten 53}
+	// {Carsten 54}
+}
+
+func Example_immutability_lenses() {
+
+	// Lens[Person, string]
+	nameLens := L.MakeLens(Person.GetName, Person.SetName)
+	// Lens[Client, Person]
+	personLens := L.MakeLens(Client.GetPerson, Client.SetPerson)
+
+	// Lens[Client, string]
+	clientNameLens := F.Pipe1(
+		personLens,
+		L.Compose[Client](nameLens),
+	)
+	// func(Client) Client
+	upperName := L.Modify[Client](strings.ToUpper)(clientNameLens)
+
+	c1 := MakeClient("Böblingen", "Carsten", 53)
+
+	c2 := upperName(c1)
+
+	fmt.Println(c1)
+	fmt.Println(c2)
+
+	// Output:
+	// {{Carsten 53} {Böblingen}}
+	// {{CARSTEN 53} {Böblingen}}
+}