Deprecate Result.of in favour of runCatching factory function

Matches Kotlin's stdlib and becomes top-level

example/src/main/kotlin/com/github/michaelbull/result/example/service/CustomerService.kt

@@ -15,6 +15,7 @@ import com.github.michaelbull.result.map
 import com.github.michaelbull.result.mapAll
 import com.github.michaelbull.result.mapBoth
 import com.github.michaelbull.result.mapError
+import com.github.michaelbull.result.runCatching
 import com.github.michaelbull.result.toResultOr
 import java.sql.SQLTimeoutException
 
@@ -22,7 +23,7 @@ object CustomerService {
     private val repository = InMemoryCustomerRepository()
 
     fun getAll(): Result<Collection<Customer>, DomainMessage> {
-        return Result.of(repository::findAll)
+        return runCatching(repository::findAll)
             .mapError(::exceptionToDomainMessage)
             .mapAll(Customer.Companion::from)
     }
@@ -40,12 +41,12 @@ object CustomerService {
     }
 
     private fun updateCustomer(entity: CustomerEntity, old: Customer, new: Customer) =
-        Result.of { repository.update(entity) }
+        runCatching { repository.update(entity) }
             .map { differenceBetween(old, new) }
             .mapError(::exceptionToDomainMessage)
 
     private fun createCustomer(entity: CustomerEntity) =
-        Result.of { repository.insert(entity) }
+        runCatching { repository.insert(entity) }
             .map { CustomerCreated }
             .mapError(::exceptionToDomainMessage)
 

src/main/kotlin/com/github/michaelbull/result/Factory.kt

@@ -0,0 +1,53 @@
+package com.github.michaelbull.result
+
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+
+/**
+ * Calls the specified function [block] and returns its encapsulated result if
+ * invocation was successful, catching and encapsulating any thrown exception
+ * as a failure.
+ */
+inline fun <V> runCatching(block: () -> V): Result<V, Throwable> {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+
+    return try {
+        Ok(block())
+    } catch (e: Throwable) {
+        Err(e)
+    }
+}
+
+/**
+ * Calls the specified function [block] with `this` value as its receiver and
+ * returns its encapsulated result if invocation was successful, catching and
+ * encapsulating any thrown exception as a failure.
+ */
+inline infix fun <T, V> T.runCatching(block: T.() -> V): Result<V, Throwable> {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+
+    return try {
+        Ok(block())
+    } catch (e: Throwable) {
+        Err(e)
+    }
+}
+
+/**
+ * Converts a nullable of type [V] to a [Result]. Returns [Ok] if the value is
+ * non-null, otherwise the supplied [error].
+ */
+inline infix fun <V, E> V?.toResultOr(error: () -> E): Result<V, E> {
+    contract {
+        callsInPlace(error, InvocationKind.AT_MOST_ONCE)
+    }
+
+    return when (this) {
+        null -> Err(error())
+        else -> Ok(this)
+    }
+}

src/main/kotlin/com/github/michaelbull/result/Result.kt

@@ -1,8 +1,5 @@
 package com.github.michaelbull.result
 
-import kotlin.contracts.InvocationKind
-import kotlin.contracts.contract
-
 /**
  * [Result] is a type that represents either success ([Ok]) or failure ([Err]).
  *
@@ -17,6 +14,7 @@ sealed class Result<out V, out E> {
          * Invokes a [function] and wraps it in a [Result], returning an [Err]
          * if an [Exception] was thrown, otherwise [Ok].
          */
+        @Deprecated("Use top-level runCatching instead", ReplaceWith("runCatching(function)"))
         inline fun <V> of(function: () -> V): Result<V, Exception> {
             return try {
                 Ok(function.invoke())
@@ -36,18 +34,3 @@ data class Ok<out V>(val value: V) : Result<V, Nothing>()
  * Represents a failed [Result], containing an [error].
  */
 data class Err<out E>(val error: E) : Result<Nothing, E>()
-
-/**
- * Converts a nullable of type [V] to a [Result]. Returns [Ok] if the value is
- * non-null, otherwise the supplied [error].
- */
-inline infix fun <V, E> V?.toResultOr(error: () -> E): Result<V, E> {
-    contract {
-        callsInPlace(error, InvocationKind.AT_MOST_ONCE)
-    }
-
-    return when (this) {
-        null -> Err(error())
-        else -> Ok(this)
-    }
-}

src/test/kotlin/com/github/michaelbull/result/FactoryTest.kt

@@ -4,12 +4,12 @@ import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertSame
 
-class ResultTest {
-    class Of {
+class FactoryTest {
+    class RunCatching {
         @Test
         fun returnsOkIfInvocationSuccessful() {
             val callback = { "example" }
-            val result = Result.of(callback)
+            val result = runCatching(callback)
 
             assertEquals(
                 expected = "example",
@@ -21,7 +21,7 @@ class ResultTest {
         fun returnsErrIfInvocationFails() {
             val exception = IllegalArgumentException("throw me")
             val callback = { throw exception }
-            val result = Result.of(callback)
+            val result = runCatching(callback)
 
             assertSame(
                 expected = exception,