initial checkin

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

option/sequence.go

@@ -0,0 +1,58 @@
+package option
+
+import (
+	Apply "github.com/ibm/fp-go/apply"
+	F "github.com/ibm/fp-go/function"
+	T "github.com/ibm/fp-go/tuple"
+)
+
+// HKTA = HKT<A>
+// HKTOA = HKT<Option<A>>
+//
+// Sequence converts an option of some higher kinded type into the higher kinded type of an option
+func Sequence[A, HKTA, HKTOA any](
+	_of func(Option[A]) HKTOA,
+	_map func(HKTA, func(A) Option[A]) HKTOA,
+) func(Option[HKTA]) HKTOA {
+	return Fold(F.Nullary2(None[A], _of), F.Bind2nd(_map, Some[A]))
+}
+
+// SequenceT converts n inputs of higher kinded types into a higher kinded types of n strongly typed values, represented as a tuple
+
+func SequenceT1[A any](a Option[A]) Option[T.Tuple1[A]] {
+	return Apply.SequenceT1(
+		MonadMap[A, T.Tuple1[A]],
+
+		a,
+	)
+}
+
+func SequenceT2[A, B any](a Option[A], b Option[B]) Option[T.Tuple2[A, B]] {
+	return Apply.SequenceT2(
+		MonadMap[A, func(B) T.Tuple2[A, B]],
+		MonadAp[B, T.Tuple2[A, B]],
+
+		a, b,
+	)
+}
+
+func SequenceT3[A, B, C any](a Option[A], b Option[B], c Option[C]) Option[T.Tuple3[A, B, C]] {
+	return Apply.SequenceT3(
+		MonadMap[A, func(B) func(C) T.Tuple3[A, B, C]],
+		MonadAp[B, func(C) T.Tuple3[A, B, C]],
+		MonadAp[C, T.Tuple3[A, B, C]],
+
+		a, b, c,
+	)
+}
+
+func SequenceT4[A, B, C, D any](a Option[A], b Option[B], c Option[C], d Option[D]) Option[T.Tuple4[A, B, C, D]] {
+	return Apply.SequenceT4(
+		MonadMap[A, func(B) func(C) func(D) T.Tuple4[A, B, C, D]],
+		MonadAp[B, func(C) func(D) T.Tuple4[A, B, C, D]],
+		MonadAp[C, func(D) T.Tuple4[A, B, C, D]],
+		MonadAp[D, T.Tuple4[A, B, C, D]],
+
+		a, b, c, d,
+	)
+}