fix availability (#4)

Author: ph1ps

Sources/AsyncAlgorithms/Retry/Backoff.swift

@@ -50,7 +50,7 @@ public protocol BackoffStrategy<Duration> {
   @usableFromInline let factor: Int
   @usableFromInline init(factor: Int, initial: Duration) {
     precondition(initial >= .zero, "Initial must be greater than or equal to 0")
-    precondition(factor >= 1, "Factor must be greater than or equal to 1")
+    precondition(factor >= .zero, "Factor must be greater than or equal to 0")
     self.current = initial
     self.factor = factor
   }
@@ -154,6 +154,10 @@ public enum Backoff {
   @inlinable public static func exponential(factor: Int, initial: Duration) -> some BackoffStrategy<Duration> {
     return ExponentialBackoffStrategy(factor: factor, initial: initial)
   }
+}
+
+@available(iOS 18.0, macCatalyst 18.0, macOS 15.0, tvOS 18.0, visionOS 2.0, watchOS 11.0, *)
+extension Backoff {
   @inlinable public static func decorrelatedJitter<RNG: RandomNumberGenerator>(factor: Int, base: Duration, using generator: RNG) -> some BackoffStrategy<Duration> {
     return DecorrelatedJitterBackoffStrategy(base: base, factor: factor, generator: generator)
   }

Sources/AsyncAlgorithms/Retry/Retry.swift

@@ -17,8 +17,7 @@ public struct RetryStrategy<Duration: DurationProtocol> {
 }
 
 @available(iOS 16.0, macCatalyst 16.0, macOS 13.0, tvOS 16.0, visionOS 1.0, watchOS 9.0, *)
-@inlinable
-public func retry<Result, ErrorType, ClockType>(
+@inlinable public func retry<Result, ErrorType, ClockType>(
   maxAttempts: Int = 3,
   tolerance: ClockType.Instant.Duration? = nil,
   clock: ClockType,
@@ -45,8 +44,7 @@ public func retry<Result, ErrorType, ClockType>(
 }
 
 @available(iOS 16.0, macCatalyst 16.0, macOS 13.0, tvOS 16.0, visionOS 1.0, watchOS 9.0, *)
-@inlinable
-public func retry<Result, ErrorType>(
+@inlinable public func retry<Result, ErrorType>(
   maxAttempts: Int = 3,
   tolerance: ContinuousClock.Instant.Duration? = nil,
   isolation: isolated (any Actor)? = #isolation,