Add attempt builder as an emperative alternative to recover

arrow-libs/core/arrow-core/api/arrow-core.api

@@ -1040,6 +1040,7 @@ public final class arrow/core/raise/RaiseKt {
 	public static final fun _foldOrThrow (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun _foldUnsafe (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun _merge (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+	public static final fun attempt (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun catch (Lkotlin/jvm/functions/Function0;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun catch (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function1;
 	public static final fun catch (Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function2;
@@ -1089,6 +1090,7 @@ public final class arrow/core/raise/RaiseKt {
 	public static final fun toResult (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static final fun toResult (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static final fun traced (Larrow/core/raise/Raise;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
+	public static final fun valueOrEmpty (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun withError (Larrow/core/raise/Raise;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun zipOrAccumulate (Larrow/core/raise/Raise;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function9;)Ljava/lang/Object;
 	public static final fun zipOrAccumulate (Larrow/core/raise/Raise;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function8;)Ljava/lang/Object;

arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Raise.kt

@@ -14,7 +14,6 @@ import arrow.core.recover
 import kotlin.coroutines.cancellation.CancellationException
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.InvocationKind.AT_MOST_ONCE
-import kotlin.contracts.InvocationKind.EXACTLY_ONCE
 import kotlin.contracts.contract
 import kotlin.experimental.ExperimentalTypeInference
 import kotlin.jvm.JvmMultifileClass
@@ -662,7 +661,8 @@ public inline fun <Error, OtherError, A> Raise<Error>.withError(
   contract {
     callsInPlace(transform, AT_MOST_ONCE)
   }
-  return recover(block) { raise(transform(it)) }
+  val error = attempt { return block(this) }
+  raise(transform(error))
 }
 
 /**
@@ -693,3 +693,41 @@ public inline fun <A> merge(
   }
   return recover(block, ::identity)
 }
+
+/**
+ * Execute the [Raise] context function resulting in an early-return to an outer scope,
+ * or any _logical error_ of type [Error].
+ * This function behaves like an imperative version of recover.
+ * <!--- INCLUDE
+ * import arrow.core.getOrElse
+ * import arrow.core.raise.attempt
+ * import arrow.core.raise.either
+ * import io.kotest.matchers.shouldBe
+ * import kotlin.random.Random
+ * -->
+ * ```kotlin
+ * val foo = either { if (Random.nextBoolean()) raise("failed") else 42 }
+ *
+ * fun test() {
+ *   either {
+ *     val msg = attempt { return@either foo.bind() }
+ *     raise(msg.toList())
+ *   } shouldBe foo.mapLeft(String::toList)
+ *
+ *   run {
+ *     attempt { return@run foo.bind() }
+ *     1
+ *   } shouldBe foo.getOrElse { 1 }
+ * }
+ *
+ * ```
+ * <!--- KNIT example-raise-dsl-13.kt -->
+ * <!--- TEST lines.isEmpty() -->
+ */
+@RaiseDSL
+public inline fun <Error> attempt(block: Raise<Error>.() -> Nothing): Error {
+  contract {
+    callsInPlace(block, AT_MOST_ONCE)
+  }
+  return merge(block)
+}

arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/RaiseAccumulate.kt

@@ -256,17 +256,17 @@ public inline fun <Error, A, B, C, D, E, F, G, H, I, J> Raise<Error>.zipOrAccumu
 ): J {
   contract { callsInPlace(block, AT_MOST_ONCE) }
   var error: Any? = EmptyValue
-  val a = recover({ action1(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val b = recover({ action2(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val c = recover({ action3(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val d = recover({ action4(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val e = recover({ action5(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val f = recover({ action6(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val g = recover({ action7(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val h = recover({ action8(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  val i = recover({ action9(RaiseAccumulate(this)) }) { error = combine(error, it.reduce(combine), combine); EmptyValue }
-  return if (error !== EmptyValue) raise(unbox<Error>(error))
-  else block(unbox(a), unbox(b), unbox(c), unbox(d), unbox(e), unbox(f), unbox(g), unbox(h), unbox(i))
+  val a = valueOrEmpty(action1) { error = combine(error, it.reduce(combine), combine) }
+  val b = valueOrEmpty(action2) { error = combine(error, it.reduce(combine), combine) }
+  val c = valueOrEmpty(action3) { error = combine(error, it.reduce(combine), combine) }
+  val d = valueOrEmpty(action4) { error = combine(error, it.reduce(combine), combine) }
+  val e = valueOrEmpty(action5) { error = combine(error, it.reduce(combine), combine) }
+  val f = valueOrEmpty(action6) { error = combine(error, it.reduce(combine), combine) }
+  val g = valueOrEmpty(action7) { error = combine(error, it.reduce(combine), combine) }
+  val h = valueOrEmpty(action8) { error = combine(error, it.reduce(combine), combine) }
+  val i = valueOrEmpty(action9) { error = combine(error, it.reduce(combine), combine) }
+  if (error !== EmptyValue) raise(unbox(error))
+  return block(unbox(a), unbox(b), unbox(c), unbox(d), unbox(e), unbox(f), unbox(g), unbox(h), unbox(i))
 }
 
 /**
@@ -487,19 +487,33 @@ public inline fun <Error, A, B, C, D, E, F, G, H, I, J> Raise<NonEmptyList<Error
 ): J {
   contract { callsInPlace(block, AT_MOST_ONCE) }
   val error: MutableList<Error> = mutableListOf()
-  val a = recover({ action1(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val b = recover({ action2(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val c = recover({ action3(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val d = recover({ action4(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val e = recover({ action5(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val f = recover({ action6(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val g = recover({ action7(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val h = recover({ action8(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
-  val i = recover({ action9(RaiseAccumulate(this)) }) { error.addAll(it); EmptyValue }
+  val a = valueOrEmpty(action1, error::addAll)
+  val b = valueOrEmpty(action2, error::addAll)
+  val c = valueOrEmpty(action3, error::addAll)
+  val d = valueOrEmpty(action4, error::addAll)
+  val e = valueOrEmpty(action5, error::addAll)
+  val f = valueOrEmpty(action6, error::addAll)
+  val g = valueOrEmpty(action7, error::addAll)
+  val h = valueOrEmpty(action8, error::addAll)
+  val i = valueOrEmpty(action9, error::addAll)
   error.toNonEmptyListOrNull()?.let { raise(it) }
   return block(unbox(a), unbox(b), unbox(c), unbox(d), unbox(e), unbox(f), unbox(g), unbox(h), unbox(i))
 }
 
+@PublishedApi
+internal inline fun <A, Error> valueOrEmpty(
+  block: RaiseAccumulate<Error>.() -> A,
+  addErrors: (NonEmptyList<Error>) -> Unit
+): Any? {
+  contract {
+    callsInPlace(block, AT_MOST_ONCE)
+    callsInPlace(addErrors, AT_MOST_ONCE)
+  }
+  val errorList = attempt { return block(RaiseAccumulate(this)) }
+  addErrors(errorList)
+  return EmptyValue
+}
+
 /**
  * Transform every element of [iterable] using the given [transform], or accumulate all the occurred errors using [combine].
  *

arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/raise/EagerEffectSpec.kt

@@ -293,4 +293,25 @@ class EagerEffectSpec {
         .get() shouldBe i
     }
   }
+
+  @Test fun attemptSuccess() = runTest {
+    checkAll(Arb.int()) { i ->
+      run { attempt<Nothing> { return@run i } } shouldBe i
+    }
+  }
+
+  @Test fun attemptRaise() = runTest {
+    checkAll(Arb.int(), Arb.string()) { i, s ->
+      run {
+        attempt { raise(i) } shouldBe i
+        s
+      } shouldBe s
+    }
+  }
+
+  @Test fun attemptNested() = runTest {
+    checkAll(Arb.int()) { i ->
+      attempt { attempt<Nothing> { raise(i) } } shouldBe i
+    }
+  }
 }

arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-raise-dsl-13.kt

@@ -0,0 +1,23 @@
+// This file was automatically generated from Raise.kt by Knit tool. Do not edit.
+package arrow.core.examples.exampleRaiseDsl13
+
+import arrow.core.getOrElse
+import arrow.core.raise.attempt
+import arrow.core.raise.either
+import io.kotest.matchers.shouldBe
+import kotlin.random.Random
+
+val foo = either { if (Random.nextBoolean()) raise("failed") else 42 }
+
+fun test() {
+  either {
+    val msg = attempt { return@either foo.bind() }
+    raise(msg.toList())
+  } shouldBe foo.mapLeft(String::toList)
+
+  run {
+    attempt { return@run foo.bind() }
+    1
+  } shouldBe foo.getOrElse { 1 }
+}
+

arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/test/RaiseKnitTest.kt

@@ -49,4 +49,8 @@ class RaiseKnitTest {
     arrow.core.examples.exampleRaiseDsl12.test()
   }
 
+  @Test fun exampleRaiseDsl13() = runTest {
+    arrow.core.examples.exampleRaiseDsl13.test()
+  }
+
 }