Skip to content

Optimize FreeApplicative.product #1921

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
kailuowang merged 1 commit into from
Sep 21, 2017
Merged

Optimize FreeApplicative.product #1921

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 16 additions & 3 deletions free/src/main/scala/cats/free/FreeApplicative.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,16 @@ sealed abstract class FreeApplicative[F[_], A] extends Product with Serializable
}
}

final def map2[B, C](fb: FA[F, B])(f: (A, B) => C): FA[F, C] =
this match {
case Pure(a) => fb.map(f(a, _))
case _ =>
fb match {
case Pure(b) => Ap(Pure(f((_: A), b)), this)
case _ => Ap(Ap(Pure((a: A) => (b: B) => f(a, b)), this), fb)
}
}

/** Interprets/Runs the sequence of operations using the semantics of `Applicative` G[_].
* Tail recursive.
*/
Expand Down Expand Up @@ -193,16 +203,19 @@ object FreeApplicative {
final def lift[F[_], A](fa: F[A]): FA[F, A] =
Lift(fa)

implicit final def freeApplicative[S[_]]: Applicative[FA[S, ?]] = {
implicit final def freeApplicative[S[_]]: Applicative[FA[S, ?]] =
new Applicative[FA[S, ?]] {
override def product[A, B](fa: FA[S, A], fb: FA[S, B]): FA[S, (A, B)] = ap(fa.map((a: A) => (b: B) => (a, b)))(fb)
override def product[A, B](fa: FA[S, A], fb: FA[S, B]): FA[S, (A, B)] =
map2(fa, fb)((_, _))

override def map[A, B](fa: FA[S, A])(f: A => B): FA[S, B] = fa.map(f)

override def ap[A, B](f: FA[S, A => B])(fa: FA[S, A]): FA[S, B] = fa.ap(f)

def pure[A](a: A): FA[S, A] = Pure(a)

override def map2[A, B, Z](fa: FA[S, A], fb: FA[S, B])(f: (A, B) => Z): FA[S, Z] =
fa.map2(fb)(f)
}
}

}