crystal.package.scala Maven / Gradle / Ivy
// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
package crystal
import cats.Applicative
import cats.Eq
import cats.InvariantSemigroupal
import cats.Monad
import cats.syntax.all.*
export syntax.*
extension [F[_]: Monad](f: F[Unit])
def when(cond: F[Boolean]): F[Unit] =
cond.flatMap(f.whenA)
extension [F[_]: Applicative](opt: Option[F[Unit]])
def orUnit: F[Unit] =
opt.getOrElse(Applicative[F].unit)
object throwable {
// Copied from cats-effect-laws utils.
given Eq[Throwable] =
new Eq[Throwable] {
def eqv(x: Throwable, y: Throwable): Boolean =
// All exceptions are non-terminating and given exceptions
// aren't values (being mutable, they implement reference
// equality), then we can't really test them reliably,
// especially due to race conditions or outside logic
// that wraps them (e.g. ExecutionException)
(x ne null) == (y ne null)
}
}
given [F[_]: Monad]: InvariantSemigroupal[ViewF[F, *]] with
def product[A, B](fa: ViewF[F, A], fb: ViewF[F, B]): ViewF[F, (A, B)] =
ViewF.apply(
fa.get -> fb.get,
(f, cb) =>
fa.modCB( // Get current a value
identity(_),
oldA =>
fb.modCB( // Get current b value
identity(_),
oldB =>
fa.modCB( // Modify underlying a value
a => f(a, oldB)._1,
(prevA, newA) =>
fb.modCB( // Modify underlying b value
b => f(oldA, b)._2,
(prevB, newB) => cb((prevA, prevB), (newA, newB))
)
)
)
)
)
def imap[A, B](fa: ViewF[F, A])(f: A => B)(g: B => A): ViewF[F, B] =
fa.zoom(f)(mod => a => g(mod(f(a))))