fix: introduce stateless iterator

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

erasure/erasure.go

@@ -0,0 +1,51 @@
+// 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 erasure
+
+import (
+	F "github.com/IBM/fp-go/function"
+)
+
+// Erase converts a variable of type T to an any by returning a pointer to that variable
+func Erase[T any](t T) any {
+	return &t
+}
+
+// Unerase converts an erased variable back to its original value
+func Unerase[T any](t any) T {
+	return *t.(*T)
+}
+
+// Erase0 converts a type safe function into an erased function
+func Erase0[T1 any](f func() T1) func() any {
+	return F.Nullary2(f, Erase[T1])
+}
+
+// Erase1 converts a type safe function into an erased function
+func Erase1[T1, T2 any](f func(T1) T2) func(any) any {
+	return F.Flow3(
+		Unerase[T1],
+		f,
+		Erase[T2],
+	)
+}
+
+// Erase2 converts a type safe function into an erased function
+func Erase2[T1, T2, T3 any](f func(T1, T2) T3) func(any, any) any {
+	return func(t1, t2 any) any {
+		return Erase(f(Unerase[T1](t1), Unerase[T2](t2)))
+	}
+}