Scala 在中列出多个匿名/下划线参数以供理解
我是Scala/functional的新手,所以我还不能使用技术语言 我的理解能力有问题Scala 在中列出多个匿名/下划线参数以供理解,scala,functional-programming,for-comprehension,doobie,Scala,Functional Programming,For Comprehension,Doobie,我是Scala/functional的新手,所以我还不能使用技术语言 我的理解能力有问题 val queries = for { _ <- createBanco _ <- createBancoMedio bankInsertions <- Update[Banco](insertStr).updateMany(NonEmptyList.fromList(createBankList(1, maxBanks)).get) mediumInsertions
val queries =
for {
_ <- createBanco
_ <- createBancoMedio
bankInsertions <- Update[Banco](insertStr).updateMany(NonEmptyList.fromList(createBankList(1, maxBanks)).get)
mediumInsertions <- Update[BancoMedio](mediumInsert).updateMany(NonEmptyList.fromList(mediumList).get)
bankCount <- BancoStatements.getCount().unique
bankGetIds <- BancoStatements.getIds(0, maxBanks).to[List]
bankSome <- BancoStatements.getSome(halfBanks).to[List]
} yield (bankCount, bankGetIds, bankSome)
//Execute database queries, saves them on tuple
val transactionResults : (Int, List[String], List[Banco]) =
queries.transact(h2Transactor).unsafeRunSync()
val查询=
为了{
_刚刚解决了这个问题,又做了一次,以便理解列表
val createList = for {
m <- createBancoMedio
b <- createBanco
} yield List(b, m)
val queries =
for {
_ <- createList ....
val createList=for{
m如果G
有一个Applicative
实例,则可以使用.sequence
将列表[G[a]]
转换为G[a]
,其中ConnectionIO执行以下操作:
val queries =
for {
_ <- List(createBanco, createBancoMedio).sequence
...
val查询=
为了{
_我必须在序列中指定G和A,但工作起来很有魅力。谢谢!(.sequence[conctionio,Int])