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Override some Option Apply/Applicative methods #3516

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merged 1 commit into from
Jul 14, 2020
Merged

Override some Option Apply/Applicative methods #3516

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42 changes: 39 additions & 3 deletions core/src/main/scala/cats/instances/option.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -46,12 +46,48 @@ trait OptionInstances extends cats.kernel.instances.OptionInstances {
}

override def map2[A, B, Z](fa: Option[A], fb: Option[B])(f: (A, B) => Z): Option[Z] =
fa.flatMap(a => fb.map(b => f(a, b)))
// we are avoiding flatMap/map to avoid allocating more closures
if (fa.isDefined && fb.isDefined) Some(f(fa.get, fb.get))
else None

override def product[A, B](fa: Option[A], fb: Option[B]): Option[(A, B)] =
// we are avoiding flatMap/map to avoid allocating more closures
if (fa.isDefined && fb.isDefined) Some((fa.get, fb.get))
else None

override def productR[A, B](fa: Option[A])(fb: Option[B]): Option[B] =
// we are avoiding flatMap/map to avoid allocating more closures
if (fa.isDefined) fb
else None

override def productL[A, B](fa: Option[A])(fb: Option[B]): Option[A] =
// we are avoiding flatMap/map to avoid allocating more closures
if (fb.isDefined) fa
else None

override def ap[A, B](f: Option[A => B])(fa: Option[A]): Option[B] =
// we are avoiding flatMap/map to avoid allocating more closures
if (f.isDefined && fa.isDefined) Some(f.get(fa.get))
else None

override def ap2[A, B, Z](ff: Option[(A, B) => Z])(fa: Option[A], fb: Option[B]): Option[Z] =
if (ff.isDefined && fa.isDefined && fb.isDefined) Some(ff.get(fa.get, fb.get))
else None

override def ifA[A](fcond: Option[Boolean])(ifTrue: Option[A], ifFalse: Option[A]): Option[A] =
if (fcond.isDefined) {
if (fcond.get) ifTrue
else ifFalse
} else None

override def map2Eval[A, B, Z](fa: Option[A], fb: Eval[Option[B]])(f: (A, B) => Z): Eval[Option[Z]] =
fa match {
case None => Now(None)
case Some(a) => fb.map(_.map(f(a, _)))
case None => Now(None)
case Some(a) =>
fb.map {
case Some(b) => Some(f(a, b))
case None => None
}
}

def coflatMap[A, B](fa: Option[A])(f: Option[A] => B): Option[B] =
Expand Down