[英]Haskell's mapM equivalent for Scala cats
Does cats provide a function equivalent to mapM in Haskell? 猫是否提供与Haskell中的mapM等效的功能? It should look like: 它应该看起来像:
def mapM[A, B, F[_], Col[_]]
(col: Col[A])(f: A => F[B])(implicit F: Applicative[F], T: Traverse[Col]): F[Col[B]] =
T.sequence[F, B](F.map(col)(f))
Unfortunately I haven't found any function like this one =( 不幸的是,我还没有找到任何像这样的函数=(
It's called traverse
: 这称为traverse
:
scala> import cats.implicits._
import cats.implicits._
scala> List(1, 2, 3).traverse(n => Option((n * 2).toString))
res1: Option[List[String]] = Some(List(2, 4, 6))
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