Facilitate mapping to arbitrary types in and/or functions

Closes #95

kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/And.kt

@@ -8,7 +8,7 @@ import kotlin.contracts.contract
  *
  * - Rust: [Result.and](https://doc.rust-lang.org/std/result/enum.Result.html#method.and)
  */
-public infix fun <V, E> Result<V, E>.and(result: Result<V, E>): Result<V, E> {
+public infix fun <V, E, U> Result<V, E>.and(result: Result<U, E>): Result<U, E> {
     return when (this) {
         is Ok -> result
         is Err -> this
@@ -16,7 +16,7 @@ public infix fun <V, E> Result<V, E>.and(result: Result<V, E>): Result<V, E> {
 }
 
 @Deprecated("Use andThen instead", ReplaceWith("andThen { result() }"))
-public inline infix fun <V, E> Result<V, E>.and(result: () -> Result<V, E>): Result<V, E> {
+public inline infix fun <V, E, U> Result<V, E>.and(result: () -> Result<U, E>): Result<U, E> {
     contract {
         callsInPlace(result, InvocationKind.AT_MOST_ONCE)
     }

kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Or.kt

@@ -8,7 +8,7 @@ import kotlin.contracts.contract
  *
  * - Rust: [Result.or](https://doc.rust-lang.org/std/result/enum.Result.html#method.or)
  */
-public infix fun <V, E> Result<V, E>.or(result: Result<V, E>): Result<V, E> {
+public infix fun <V, E, F> Result<V, E>.or(result: Result<V, F>): Result<V, F> {
     return when (this) {
         is Ok -> this
         is Err -> result
@@ -16,7 +16,7 @@ public infix fun <V, E> Result<V, E>.or(result: Result<V, E>): Result<V, E> {
 }
 
 @Deprecated("Use orElse instead", ReplaceWith("orElse { result() }"))
-public inline infix fun <V, E> Result<V, E>.or(result: () -> Result<V, E>): Result<V, E> {
+public inline infix fun <V, E, F> Result<V, E>.or(result: () -> Result<V, F>): Result<V, F> {
     contract {
         callsInPlace(result, InvocationKind.AT_MOST_ONCE)
     }
@@ -30,7 +30,7 @@ public inline infix fun <V, E> Result<V, E>.or(result: () -> Result<V, E>): Resu
  *
  * - Rust: [Result.or_else](https://doc.rust-lang.org/std/result/enum.Result.html#method.or_else)
  */
-public inline infix fun <V, E> Result<V, E>.orElse(transform: (E) -> Result<V, E>): Result<V, E> {
+public inline infix fun <V, E, F> Result<V, E>.orElse(transform: (E) -> Result<V, F>): Result<V, F> {
     contract {
         callsInPlace(transform, InvocationKind.AT_MOST_ONCE)
     }

kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/ZipTest.kt

@@ -3,6 +3,10 @@ package com.github.michaelbull.result
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
+private inline fun produce(number: Int, error: String): Result<Int, String> {
+    return Ok(number).and(Err(error))
+}
+
 class ZipTest {
 
     data class ZipData3(val a: String, val b: Int, val c: Boolean)
@@ -31,7 +35,7 @@ class ZipTest {
         fun returnsErrIfOneOfTwoErr() {
             val result = zip(
                 { Ok(10) },
-                { Ok(20).and(Err("hello")) },
+                { produce(20, "hello") },
                 Int::plus
             )
 
@@ -46,8 +50,8 @@ class ZipTest {
         @Test
         fun returnsFirstErrIfBothErr() {
             val result = zip(
-                { Ok(10).and(Err("foo")) },
+                { produce(10, "foo") },
-                { Ok(20).and(Err("bar")) },
+                { produce(20, "bar") },
                 Int::plus
             )
 
@@ -225,11 +229,11 @@ class ZipTest {
         @Test
         fun returnsAllErrsIfAllErr() {
             val result = zipOrAccumulate(
-                { Ok(10).and(Err("error one")) },
+                { produce(10, "error one") },
-                { Ok(20).and(Err("error two")) },
+                { produce(20, "error two") },
-                { Ok(30).and(Err("error three")) },
+                { produce(30, "error three") },
-                { Ok(40).and(Err("error four")) },
+                { produce(40, "error four") },
-                { Ok(50).and(Err("error five")) },
+                { produce(50, "error five") },
             ) { a, b, c, d, e ->
                 a + b + c + d + e
             }
@@ -252,7 +256,7 @@ class ZipTest {
         fun returnsOneErrsIfOneOfErr() {
             val result = zipOrAccumulate(
                 { Ok(10) },
-                { Ok(20).and(Err("only error")) },
+                { produce(20, "only error") },
                 { Ok(30) },
                 { Ok(40) },
                 { Ok(50) },
@@ -263,7 +267,7 @@ class ZipTest {
             result as Err
 
             assertEquals(
-                expected = listOf("only error",),
+                expected = listOf("only error"),
                 actual = result.error,
             )
         }