map入れ子
val fas: Future[Seq[A]] = ...
fas.map(_.map(a => ...))
for { as <- fas } yield for { a <- as } a ...
for { as <- fas } yield as map(a => ...)
val fas: Future[Seq[A]] = ...
fas.map(_.map(a => ...))
for { as <- fas } yield for { a <- as } a ...
for { as <- fas } yield as map(a => ...)