Fix Schedule type in retry methods (#297)

* Fix Schedule type in retry methods

* Add a few small tests for repeat/retry

Co-authored-by: Alberto Ballano <aballano@users.noreply.github.com>

arrow-fx-coroutines/src/main/kotlin/arrow/fx/coroutines/Schedule.kt

@@ -792,7 +792,7 @@ suspend fun <A, B, C> repeatOrElseEither(
  * Returns the result of the effect if if it was successful or re-raises the last error encountered when the schedule ends.
  */
 suspend fun <A, B> retry(
-  schedule: Schedule<A, B>,
+  schedule: Schedule<Throwable, B>,
   fa: suspend () -> A
 ): A = retryOrElse(schedule, fa) { e, _ -> throw e }
 
@@ -801,7 +801,7 @@ suspend fun <A, B> retry(
  * Also offers a function to handle errors if they are encountered during retrial.
  */
 suspend fun <A, B> retryOrElse(
-  schedule: Schedule<A, B>,
+  schedule: Schedule<Throwable, B>,
   fa: suspend () -> A,
   orElse: suspend (Throwable, B) -> A
 ): A = retryOrElseEither(schedule, fa, orElse).fold(::identity, ::identity)
@@ -812,7 +812,7 @@ suspend fun <A, B> retryOrElse(
  */
 @Suppress("UNCHECKED_CAST")
 suspend fun <A, B, C> retryOrElseEither(
-  schedule: Schedule<A, B>,
+  schedule: Schedule<Throwable, B>,
   fa: suspend () -> A,
   orElse: suspend (Throwable, B) -> C
 ): Either<C, A> {

arrow-fx-coroutines/src/test/kotlin/arrow/fx/coroutines/ScheduleTest.kt

@@ -2,6 +2,7 @@ package arrow.fx.coroutines
 
 import arrow.core.Either
 import arrow.core.Eval
+import io.kotest.assertions.fail
 import io.kotest.matchers.shouldBe
 import kotlin.math.pow
 
@@ -175,10 +176,21 @@ class ScheduleTest : ArrowFxSpec(spec = {
     l shouldBe Either.Left(stop)
   }
 
+  "repeat fails fast on errors" {
+    val ex = Throwable("Hello")
+    repeatOrElseEither(Schedule.recurs(0), { throw ex }) { exc, _ -> exc }
+      .fold({ it shouldBe ex }, { fail("The impossible happened") })
+  }
+
+  "repeat should run the schedule with the correct input" {
+    var i = 0
+    repeat(Schedule.recurs<Int>(10).zipRight(Schedule.collect())) { i++ } shouldBe (0..10).toList()
+  }
+
   "retry is stack-safe" {
     val count = Atomic(0)
     val l = Either.catch {
-      val n: Nothing = retry(Schedule.recurs(20_000)) {
+      retry(Schedule.recurs(20_000)) {
         count.updateAndGet { it + 1 }
         throw exception
       }
@@ -187,6 +199,18 @@ class ScheduleTest : ArrowFxSpec(spec = {
     l shouldBe Either.Left(exception)
     count.get() shouldBe 20_001
   }
+
+  "retry succeeds if no exception is thrown" {
+    retry(Schedule.recurs(0)) { 1 } shouldBe 1
+  }
+
+  "retryOrElseEither runs the schedule with the correct input and runs the orElse handler if it does not retry" {
+    val ex = Throwable("Hello")
+    val res = retryOrElseEither<Int, Int, Throwable>(Schedule.recurs(0), {
+      throw ex
+    }) { e, _ -> e }
+    res.fold({ it shouldBe ex }, { fail("The impossible happened") })
+  }
 })
 
 private fun fibs(one: Long): Sequence<Long> = generateSequence(Pair(0L, one)) { (a, b) ->