in src/main/scala/com/twitter/stitch/Arrow.scala [2819:2865]
def join[A, B, C, D, E, F, G](
a1: Arrow[A, B],
a2: Arrow[A, C],
a3: Arrow[A, D],
a4: Arrow[A, E],
a5: Arrow[A, F],
a6: Arrow[A, G]
): Arrow[A, (B, C, D, E, F, G)] =
joinMap(a1, a2, a3, a4, a5, a6)((_, _, _, _, _, _))
/**
* `Arrow.joinMap(a1, a2, a3, a4, a5, a6)(k)` is equivalent to
* `Arrow.join(a1, a2, a3, a4, a5, a6).map(k.tupled)`,
* but avoids allocating an intermediate tuple.
*/
def joinMap[A, B, C, D, E, F, G, Z](
a1: Arrow[A, B],
a2: Arrow[A, C],
a3: Arrow[A, D],
a4: Arrow[A, E],
a5: Arrow[A, F],
a6: Arrow[A, G]
)(
k: (B, C, D, E, F, G) => Z
): Arrow[A, Z] =
(a1, a2, a3, a4, a5, a6) match {
case (Const(Throw(e)), _, _, _, _, _) => exception(e)
case (_, Const(Throw(e)), _, _, _, _) => exception(e)
case (_, _, Const(Throw(e)), _, _, _) => exception(e)
case (_, _, _, Const(Throw(e)), _, _) => exception(e)
case (_, _, _, _, Const(Throw(e)), _) => exception(e)
case (_, _, _, _, _, Const(Throw(e))) => exception(e)
case (Const(Return(v1)), _, _, _, _, _) =>
joinMap(a2, a3, a4, a5, a6) { (v2, v3, v4, v5, v6) => k(v1, v2, v3, v4, v5, v6) }
case (_, Const(Return(v2)), _, _, _, _) =>
joinMap(a1, a3, a4, a5, a6) { (v1, v3, v4, v5, v6) => k(v1, v2, v3, v4, v5, v6) }
case (_, _, Const(Return(v3)), _, _, _) =>
joinMap(a1, a2, a4, a5, a6) { (v1, v2, v4, v5, v6) => k(v1, v2, v3, v4, v5, v6) }
case (_, _, _, Const(Return(v4)), _, _) =>
joinMap(a1, a2, a3, a5, a6) { (v1, v2, v3, v5, v6) => k(v1, v2, v3, v4, v5, v6) }
case (_, _, _, _, Const(Return(v5)), _) =>
joinMap(a1, a2, a3, a4, a6) { (v1, v2, v3, v4, v6) => k(v1, v2, v3, v4, v5, v6) }
case (_, _, _, _, _, Const(Return(v6))) =>
joinMap(a1, a2, a3, a4, a5) { (v1, v2, v3, v4, v5) => k(v1, v2, v3, v4, v5, v6) }
case _ =>
JoinMap6(a1, a2, a3, a4, a5, a6, k)
}