initial checkin

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

either/logger.go

@@ -0,0 +1,33 @@
+package either
+
+import (
+	"log"
+
+	F "github.com/ibm/fp-go/function"
+	L "github.com/ibm/fp-go/logging"
+)
+
+func _log[E, A any](left func(string, ...any), right func(string, ...any), prefix string) func(Either[E, A]) Either[E, A] {
+	return Fold(
+		func(e E) Either[E, A] {
+			left("%s: %v", prefix, e)
+			return Left[E, A](e)
+		},
+		func(a A) Either[E, A] {
+			right("%s: %v", prefix, a)
+			return Right[E](a)
+		})
+}
+
+func Logger[E, A any](loggers ...*log.Logger) func(string) func(Either[E, A]) Either[E, A] {
+	left, right := L.LoggingCallbacks(loggers...)
+	return func(prefix string) func(Either[E, A]) Either[E, A] {
+		delegate := _log[E, A](left, right, prefix)
+		return func(ma Either[E, A]) Either[E, A] {
+			return F.Pipe1(
+				delegate(ma),
+				ChainTo[E, A](ma),
+			)
+		}
+	}
+}