FoldableOps

Value Members

1. final def !=(arg0: Any): Boolean

   

   Definition Classes

   Any

2. final def ##(): Int

   

   Definition Classes

   Any

3. final def ==(arg0: Any): Boolean

   

   Definition Classes

   Any

4. final def asInstanceOf[T0]: T0

   

   Definition Classes

   Any

5. def collectFirstSomeM[G[_], B](f: (A) ⇒ G[Option[B]])(implicit F: Foldable[F], G: Monad[G]): G[Option[B]]

   

   Monadic version of collectFirstSome.

   Monadic version of collectFirstSome.

   If there are no elements, the result is None. collectFirstSomeM short-circuits, i.e. once a Some element is found, no further effects are produced.

   For example:

   scala> import cats.implicits._
   scala> def parseInt(s: String): Either[String, Int] = Either.catchOnly[NumberFormatException](s.toInt).leftMap(_.getMessage)
   scala> val keys1 = List("1", "2", "4", "5")
   scala> val map1 = Map(4 -> "Four", 5 -> "Five")
   scala> keys1.collectFirstSomeM(parseInt(_) map map1.get)
   res0: scala.util.Either[String,Option[String]] = Right(Some(Four))
   
   scala> val map2 = Map(6 -> "Six", 7 -> "Seven")
   scala> keys1.collectFirstSomeM(parseInt(_) map map2.get)
   res1: scala.util.Either[String,Option[String]] = Right(None)
   
   scala> val keys2 = List("1", "x", "4", "5")
   scala> keys2.collectFirstSomeM(parseInt(_) map map1.get)
   res2: scala.util.Either[String,Option[String]] = Left(For input string: "x")
   
   scala> val keys3 = List("1", "2", "4", "x")
   scala> keys3.collectFirstSomeM(parseInt(_) map map1.get)
   res3: scala.util.Either[String,Option[String]] = Right(Some(Four))

6. def collectFold[M](f: PartialFunction[A, M])(implicit F: Foldable[F], M: Monoid[M]): M

   

   Tear down a subset of this structure using a PartialFunction.

   Tear down a subset of this structure using a PartialFunction.

   scala> import cats.implicits._
   scala> val xs = List(1, 2, 3, 4)
   scala> xs.collectFold { case n if n % 2 == 0 => n }
   res0: Int = 6

7. def collectSomeFold[M](f: (A) ⇒ Option[M])(implicit F: Foldable[F], M: Monoid[M]): M

   

   Tear down a subset of this structure using a A => Option[M].

   Tear down a subset of this structure using a A => Option[M].

   scala> import cats.implicits._
   scala> val xs = List(1, 2, 3, 4)
   scala> def f(n: Int): Option[Int] = if (n % 2 == 0) Some(n) else None
   scala> xs.collectSomeFold(f)
   res0: Int = 6

8. def contains_(v: A)(implicit ev: Eq[A], F: Foldable[F]): Boolean

   

   test if F[A] contains an A, named contains_ to avoid conflict with existing contains which uses universal equality

   test if F[A] contains an A, named contains_ to avoid conflict with existing contains which uses universal equality

   Example:

   scala> import cats.implicits._
   
   scala> val l: List[Int] = List(1, 2, 3, 4)
   scala> l.contains_(1)
   res0: Boolean = true
   scala> l.contains_(5)
   res1: Boolean = false

9. def findM[G[_]](p: (A) ⇒ G[Boolean])(implicit F: Foldable[F], G: Monad[G]): G[Option[A]]

   

   Find the first element matching the effectful predicate, if one exists.

   Find the first element matching the effectful predicate, if one exists.

   If there are no elements, the result is None. findM short-circuits, i.e. once an element is found, no further effects are produced.

   For example:

   scala> import cats.implicits._
   scala> val list = List(1,2,3,4)
   scala> list.findM(n => (n >= 2).asRight[String])
   res0: Either[String,Option[Int]] = Right(Some(2))
   
   scala> list.findM(n => (n > 4).asRight[String])
   res1: Either[String,Option[Int]] = Right(None)
   
   scala> list.findM(n => Either.cond(n < 3, n >= 2, "error"))
   res2: Either[String,Option[Int]] = Right(Some(2))
   
   scala> list.findM(n => Either.cond(n < 3, false, "error"))
   res3: Either[String,Option[Int]] = Left(error)

10. def foldSmash(prefix: A, delim: A, suffix: A)(implicit A: Monoid[A], F: Foldable[F]): A

    

    Intercalate with a prefix and a suffix

    Intercalate with a prefix and a suffix

    Example:

    scala> import cats.implicits._
    
    scala> val l: List[String] = List("1", "2", "3")
    scala> l.foldSmash("List(", ",", ")")
    res0: String = List(1,2,3)

11. def foldl[B](b: B)(f: (B, A) ⇒ B)(implicit F: Foldable[F]): B

    

12. def foldr[B](b: Eval[B])(f: (A, Eval[B]) ⇒ Eval[B])(implicit F: Foldable[F]): Eval[B]

    

13. def getClass(): Class[_ <: AnyVal]

    

    Definition Classes

    AnyVal → Any

14. final def isInstanceOf[T0]: Boolean

    

    Definition Classes

    Any

15. def mkString_(prefix: String, delim: String, suffix: String)(implicit A: Show[A], F: Foldable[F]): String

    

    Make a string using Show, prefix, delimiter, and suffix.

    Make a string using Show, prefix, delimiter, and suffix.

    Named as mkString_ to avoid conflict.

    Example:

    scala> import cats.implicits._
    
    scala> val l: List[Int] = List(1, 2, 3)
    scala> l.mkString_("L[", ";", "]")
    res0: String = L[1;2;3]
    scala> val el: List[Int] = List()
    scala> el.mkString_("L[", ";", "]")
    res1: String = L[]

16. def toString(): String

    

    Definition Classes

    Any