fix: initial checkin of v2

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

v2/function/function.go

@@ -0,0 +1,68 @@
+// 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 function
+
+// Identity returns the value 'a'
+func Identity[A any](a A) A {
+	return a
+}
+
+// Constant creates a nullary function that returns the constant value 'a'
+func Constant[A any](a A) func() A {
+	return func() A {
+		return a
+	}
+}
+
+// Constant1 creates a unary function that returns the constant value 'a' and ignores its input
+func Constant1[B, A any](a A) func(B) A {
+	return func(_ B) A {
+		return a
+	}
+}
+
+// Constant2 creates a binary function that returns the constant value 'a' and ignores its inputs
+func Constant2[B, C, A any](a A) func(B, C) A {
+	return func(_ B, _ C) A {
+		return a
+	}
+}
+
+func IsNil[A any](a *A) bool {
+	return a == nil
+}
+
+func IsNonNil[A any](a *A) bool {
+	return a != nil
+}
+
+// Swap returns a new binary function that changes the order of input parameters
+func Swap[T1, T2, R any](f func(T1, T2) R) func(T2, T1) R {
+	return func(t2 T2, t1 T1) R {
+		return f(t1, t2)
+	}
+}
+
+// First returns the first out of two input values
+func First[T1, T2 any](t1 T1, _ T2) T1 {
+	return t1
+}
+
+// Second returns the second out of two input values
+// Identical to [SK]
+func Second[T1, T2 any](_ T1, t2 T2) T2 {
+	return t2
+}