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joel113/forcomp.scala

Forked from linasm/forcomp.scala
Created October 8, 2021 20:59
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Revisions

  1. @linasm linasm revised this gist Jan 28, 2019. 1 changed file with 2 additions and 0 deletions.
    2 changes: 2 additions & 0 deletions forcomp.scala
    View file
    Original file line number Diff line number Diff line change
    @@ -46,6 +46,8 @@ for {
    y3.flatMap(a => y4.map(b => a * b))

    // combining Perhaps with Try:
    import scala.util.Try

    for {
    a <- y4
    } yield for {
  2. @linasm linasm revised this gist Jan 28, 2019. 1 changed file with 13 additions and 0 deletions.
    13 changes: 13 additions & 0 deletions forcomp.scala
    View file
    Original file line number Diff line number Diff line change
    @@ -45,6 +45,19 @@ for {

    y3.flatMap(a => y4.map(b => a * b))

    // combining Perhaps with Try:
    for {
    a <- y4
    } yield for {
    b <- Try(100 / a)
    } yield s"100/$a=$b" // YesItIs(Success(100/4=25))

    y4.map { a =>
    Try(100 / a).map { b =>
    s"100/$a=$b"
    }
    }

    // withFilter:
    for {
    a <- y3
  3. @linasm linasm revised this gist Jan 28, 2019. 1 changed file with 8 additions and 8 deletions.
    16 changes: 8 additions & 8 deletions forcomp.scala
    View file
    Original file line number Diff line number Diff line change
    @@ -6,17 +6,17 @@ sealed abstract class Perhaps[+A] {
    }

    case class YesItIs[A](value: A) extends Perhaps[A] {
    override def foreach(f: (A) => Unit): Unit = f(value)
    override def map[B](f: (A) => B): Perhaps[B] = YesItIs(f(value))
    override def flatMap[B](f: (A) => Perhaps[B]): Perhaps[B] = f(value)
    override def withFilter(f: (A) => Boolean): Perhaps[A] = if (f(value)) this else Nope
    override def foreach(f: A => Unit): Unit = f(value)
    override def map[B](f: A => B): Perhaps[B] = YesItIs(f(value))
    override def flatMap[B](f: A => Perhaps[B]): Perhaps[B] = f(value)
    override def withFilter(f: A => Boolean): Perhaps[A] = if (f(value)) this else Nope
    }

    case object Nope extends Perhaps[Nothing] {
    override def foreach(f: (Nothing) => Unit): Unit = ()
    override def map[B](f: (Nothing) => B): Perhaps[B] = this
    override def flatMap[B](f: (Nothing) => Perhaps[B]): Perhaps[B] = this
    override def withFilter(f: (Nothing) => Boolean): Perhaps[Nothing] = this
    override def foreach(f: Nothing => Unit): Unit = ()
    override def map[B](f: Nothing => B): Perhaps[B] = this
    override def flatMap[B](f: Nothing => Perhaps[B]): Perhaps[B] = this
    override def withFilter(f: Nothing => Boolean): Perhaps[Nothing] = this
    }

    val y3 = YesItIs(3)
  4. @linasm linasm created this gist Nov 21, 2018.
    69 changes: 69 additions & 0 deletions forcomp.scala
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,69 @@
    sealed abstract class Perhaps[+A] {
    def foreach(f: A => Unit): Unit
    def map[B](f: A => B): Perhaps[B]
    def flatMap[B](f: A => Perhaps[B]): Perhaps[B]
    def withFilter(f: A => Boolean): Perhaps[A]
    }

    case class YesItIs[A](value: A) extends Perhaps[A] {
    override def foreach(f: (A) => Unit): Unit = f(value)
    override def map[B](f: (A) => B): Perhaps[B] = YesItIs(f(value))
    override def flatMap[B](f: (A) => Perhaps[B]): Perhaps[B] = f(value)
    override def withFilter(f: (A) => Boolean): Perhaps[A] = if (f(value)) this else Nope
    }

    case object Nope extends Perhaps[Nothing] {
    override def foreach(f: (Nothing) => Unit): Unit = ()
    override def map[B](f: (Nothing) => B): Perhaps[B] = this
    override def flatMap[B](f: (Nothing) => Perhaps[B]): Perhaps[B] = this
    override def withFilter(f: (Nothing) => Boolean): Perhaps[Nothing] = this
    }

    val y3 = YesItIs(3)
    val y4 = YesItIs(4)
    val n = Nope

    // foreach:
    for {
    a <- y3
    } println(a)

    y3.foreach(a => println(a))

    // map:
    for {
    a <- y3
    } yield a * a

    y3.map(a => a * a)

    // flatMap/map:
    for {
    a <- y3
    b <- y4
    } yield a * b

    y3.flatMap(a => y4.map(b => a * b))

    // withFilter:
    for {
    a <- y3
    if a > 1
    b <- y4
    } yield a * b

    y3.withFilter(a => a > 1).flatMap(a => y4.map(b => a * b))

    // assignment:
    for {
    a <- y3
    b <- y4
    c = a * b
    } yield c

    y3.flatMap { a =>
    y4.map { b =>
    val c = a * b
    c
    }
    }