fix: add more examples

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

option/examples_create_test.go

@@ -0,0 +1,55 @@
+// 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 option
+
+import "fmt"
+
+func ExampleOption_creation() {
+
+	// Build an Option
+	none1 := None[int]()
+	some1 := Some("value")
+
+	// Build from a value
+	fromNillable := FromNillable[string]
+	nonFromNil := fromNillable(nil) // None[*string]
+	value := "value"
+	someFromPointer := fromNillable(&value) // Some[*string](xxx)
+
+	// some predicate
+	isEven := func(num int) bool {
+		return num%2 == 0
+	}
+
+	fromEven := FromPredicate(isEven)
+	noneFromPred := fromEven(3) // None[int]
+	someFromPred := fromEven(4) // Some[int](4)
+
+	fmt.Println(none1)
+	fmt.Println(some1)
+	fmt.Println(nonFromNil)
+	fmt.Println(IsSome(someFromPointer))
+	fmt.Println(noneFromPred)
+	fmt.Println(someFromPred)
+
+	// Output:
+	// None[int]
+	// Some[string](value)
+	// None[*string]
+	// true
+	// None[int]
+	// Some[int](4)
+}