Add module for functional manipulation (#21)

* Add module for functional manipulation

* Dump API

* Readme fix and remove unused block in gradle

* Codecov fix and repeat requirement message update

README.md

@@ -10,12 +10,16 @@ Toolbox of utilities/helpers for Kotlin development.
 - [`coroutines`](coroutines) - Tools/utilities for [Coroutines]  
 ![badge][badge-js]
 ![badge][badge-jvm]
-![badge][badge-macos]
+![badge][badge-mac]
+
+- [`functional`](functional) - Tools/utilities for manipulating functions  
+![badge][badge-js]
+![badge][badge-jvm]
 
 - [`test`](test) - Utilities for test suites  
 ![badge][badge-js]
 ![badge][badge-jvm]
-![badge][badge-macos]
+![badge][badge-mac]
 
 
 [Collections]: https://kotlinlang.org/docs/reference/collections-overview.html

codecov.yml

@@ -4,3 +4,4 @@ coverage:
 fixes:
   - "com/juul/tuulbox/collections::"
   - "com/juul/tuulbox/coroutines/flow::"
+  - "com/juul/tuulbox/functional::"

functional/README.md

@@ -0,0 +1,61 @@
+![badge-js]
+![badge-jvm]
+
+# Functional
+
+Tool box with utilities for manipulating functions.
+For a full functional ecosystem, complete with `Monad` and the like, prefer [Arrow](https://arrow-kt.io/).
+
+## Installation
+
+### Gradle
+
+Artifacts are hosted on GitHub packages, which can be configured as follows:
+
+```kotlin
+import java.net.URI
+
+repositories {
+    maven {
+        url = URI("https://maven.pkg.github.com/juullabs/android-github-packages")
+        credentials {
+            username = findProperty("github.packages.username") as String
+            password = findProperty("github.packages.password") as String
+        }
+    }
+}
+```
+
+Then the needed artifact(s) can be defined as dependencies.
+
+**Multiplatform projects**
+
+```kotlin
+kotlin {
+    sourceSets {
+        val commonMain by getting {
+            implementation("com.juul.tuulbox:functional:$version")
+        }
+    }
+}
+```
+
+**Platform-specific projects**
+
+```kotlin
+dependencies {
+    implementation("com.juul.tuulbox:functional-$platform:$version")
+}
+```
+
+
+[badge-android]: http://img.shields.io/badge/platform-android-6EDB8D.svg?style=flat
+[badge-ios]: http://img.shields.io/badge/platform-ios-CDCDCD.svg?style=flat
+[badge-js]: http://img.shields.io/badge/platform-js-F8DB5D.svg?style=flat
+[badge-jvm]: http://img.shields.io/badge/platform-jvm-DB413D.svg?style=flat
+[badge-linux]: http://img.shields.io/badge/platform-linux-2D3F6C.svg?style=flat
+[badge-windows]: http://img.shields.io/badge/platform-windows-4D76CD.svg?style=flat
+[badge-mac]: http://img.shields.io/badge/platform-macos-111111.svg?style=flat
+[badge-watchos]: http://img.shields.io/badge/platform-watchos-C0C0C0.svg?style=flat
+[badge-tvos]: http://img.shields.io/badge/platform-tvos-808080.svg?style=flat
+[badge-wasm]: https://img.shields.io/badge/platform-wasm-624FE8.svg?style=flat

functional/api/functional.api

@@ -0,0 +1,59 @@
+public final class com/juul/tuulbox/functional/ComposeKt {
+	public static final fun of (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Lkotlin/jvm/functions/Function1;
+	public static final fun then (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Lkotlin/jvm/functions/Function1;
+}
+
+public final class com/juul/tuulbox/functional/CurryKt {
+	public static final fun curry (Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function1;
+	public static final fun curry (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function1;
+	public static final fun curry (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function1;
+	public static final fun curry (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function1;
+	public static final fun curry (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function1;
+	public static final fun curryFirst (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function1;
+	public static final fun curryFirst (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function1;
+	public static final fun curryFirst (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function1;
+	public static final fun curryFirst (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function1;
+}
+
+public final class com/juul/tuulbox/functional/MemoizeKt {
+	public static final fun memoize (Lkotlin/jvm/functions/Function0;)Lkotlin/jvm/functions/Function0;
+	public static final fun memoize (Lkotlin/jvm/functions/Function1;)Lkotlin/jvm/functions/Function1;
+	public static final fun memoize (Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function2;
+	public static final fun memoize (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function3;
+	public static final fun memoize (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function4;
+	public static final fun memoize (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function5;
+	public static final fun memoize (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function6;
+}
+
+public final class com/juul/tuulbox/functional/PartialApplyKt {
+	public static final fun partialApply (Lkotlin/jvm/functions/Function1;Ljava/lang/Object;)Lkotlin/jvm/functions/Function0;
+	public static final fun partialApply (Lkotlin/jvm/functions/Function2;Ljava/lang/Object;)Lkotlin/jvm/functions/Function1;
+	public static final fun partialApply (Lkotlin/jvm/functions/Function3;Ljava/lang/Object;)Lkotlin/jvm/functions/Function2;
+	public static final fun partialApply (Lkotlin/jvm/functions/Function4;Ljava/lang/Object;)Lkotlin/jvm/functions/Function3;
+	public static final fun partialApply (Lkotlin/jvm/functions/Function5;Ljava/lang/Object;)Lkotlin/jvm/functions/Function4;
+	public static final fun partialApply (Lkotlin/jvm/functions/Function6;Ljava/lang/Object;)Lkotlin/jvm/functions/Function5;
+}
+
+public final class com/juul/tuulbox/functional/RepeatKt {
+	public static final fun repeat (Lkotlin/jvm/functions/Function1;I)Lkotlin/jvm/functions/Function1;
+}
+
+public final class com/juul/tuulbox/functional/ReverseKt {
+	public static final fun reverse (Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function2;
+	public static final fun reverse (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function3;
+	public static final fun reverse (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function4;
+	public static final fun reverse (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function5;
+	public static final fun reverse (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function6;
+}
+
+public final class com/juul/tuulbox/functional/RotateKt {
+	public static final fun rotate (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function3;
+	public static final fun rotate (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function4;
+	public static final fun rotate (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function5;
+	public static final fun rotate (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function6;
+	public static final fun rotateBack (Lkotlin/jvm/functions/Function3;)Lkotlin/jvm/functions/Function3;
+	public static final fun rotateBack (Lkotlin/jvm/functions/Function4;)Lkotlin/jvm/functions/Function4;
+	public static final fun rotateBack (Lkotlin/jvm/functions/Function5;)Lkotlin/jvm/functions/Function5;
+	public static final fun rotateBack (Lkotlin/jvm/functions/Function6;)Lkotlin/jvm/functions/Function6;
+}
+

functional/build.gradle.kts

@@ -0,0 +1,38 @@
+plugins {
+    kotlin("multiplatform")
+    id("org.jmailen.kotlinter")
+    jacoco
+    `maven-publish`
+}
+
+apply(from = rootProject.file("gradle/jacoco.gradle.kts"))
+apply(from = rootProject.file("gradle/publish.gradle.kts"))
+
+kotlin {
+    explicitApi()
+
+    jvm()
+    js().browser()
+
+    sourceSets {
+        val commonTest by getting {
+            dependencies {
+                implementation(project(":test"))
+                implementation(kotlin("test-common"))
+                implementation(kotlin("test-annotations-common"))
+            }
+        }
+
+        val jvmTest by getting {
+            dependencies {
+                implementation(kotlin("test-junit"))
+            }
+        }
+
+        val jsTest by getting {
+            dependencies {
+                implementation(kotlin("test-js"))
+            }
+        }
+    }
+}

functional/src/commonMain/kotlin/Compose.kt

@@ -0,0 +1,9 @@
+package com.juul.tuulbox.functional
+
+/** Compose two functions. [this] is called first, and then [second] is called with the result. */
+public fun <I1, I2, O> ((I1) -> I2).then(second: (I2) -> O): (I1) -> O =
+    { i1 -> second(this(i1)) }
+
+/** Compose two functions. [first] is called first, and then [this] is called with the result. */
+public fun <I1, I2, O> ((I2) -> O).of(first: (I1) -> I2): (I1) -> O =
+    { i1 -> this(first(i1)) }

functional/src/commonMain/kotlin/Curry.kt

@@ -0,0 +1,37 @@
+package com.juul.tuulbox.functional
+
+/** Curry a two-argument function. */
+public fun <I1, I2, O> ((I1, I2) -> O).curry(): (I1) -> (I2) -> O =
+    { i1 -> { i2 -> this(i1, i2) } }
+
+/** Curry a three-argument function. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).curry(): (I1) -> (I2) -> (I3) -> O =
+    { i1 -> { i2 -> { i3 -> this(i1, i2, i3) } } }
+
+/** Curry a four-argument function. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).curry(): (I1) -> (I2) -> (I3) -> (I4) -> O =
+    { i1 -> { i2 -> { i3 -> { i4 -> this(i1, i2, i3, i4) } } } }
+
+/** Curry a five-argument function. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).curry(): (I1) -> (I2) -> (I3) -> (I4) -> (I5) -> O =
+    { i1 -> { i2 -> { i3 -> { i4 -> { i5 -> this(i1, i2, i3, i4, i5) } } } } }
+
+/** Curry a six-argument function. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).curry(): (I1) -> (I2) -> (I3) -> (I4) -> (I5) -> (I6) -> O =
+    { i1 -> { i2 -> { i3 -> { i4 -> { i5 -> { i6 -> this(i1, i2, i3, i4, i5, i6) } } } } } }
+
+/** Curry the first argument of a three-argument function. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).curryFirst(): (I1) -> (I2, I3) -> O =
+    { i1 -> { i2, i3 -> this(i1, i2, i3) } }
+
+/** Curry the first argument of a four-argument function. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).curryFirst(): (I1) -> (I2, I3, I4) -> O =
+    { i1 -> { i2, i3, i4 -> this(i1, i2, i3, i4) } }
+
+/** Curry the first argument of a five-argument function. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).curryFirst(): (I1) -> (I2, I3, I4, I5) -> O =
+    { i1 -> { i2, i3, i4, i5 -> this(i1, i2, i3, i4, i5) } }
+
+/** Curry the first argument of a six-argument function. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).curryFirst(): (I1) -> (I2, I3, I4, I5, I6) -> O =
+    { i1 -> { i2, i3, i4, i5, i6 -> this(i1, i2, i3, i4, i5, i6) } }

functional/src/commonMain/kotlin/Memoize.kt

@@ -0,0 +1,46 @@
+package com.juul.tuulbox.functional
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <O> (() -> O).memoize(): () -> O {
+    val value by lazy { this() }
+    return { value }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, O> ((I1) -> O).memoize(): (I1) -> O {
+    val cache = mutableMapOf<I1, O>()
+    return { i1 -> cache.getOrPut(i1) { this(i1) } }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, I2, O> ((I1, I2) -> O).memoize(): (I1, I2) -> O {
+    val cache = mutableMapOf<Pair<I1, I2>, O>()
+    return { i1, i2 -> cache.getOrPut(Pair(i1, i2)) { this(i1, i2) } }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).memoize(): (I1, I2, I3) -> O {
+    val cache = mutableMapOf<Triple<I1, I2, I3>, O>()
+    return { i1, i2, i3 -> cache.getOrPut(Triple(i1, i2, i3)) { this(i1, i2, i3) } }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).memoize(): (I1, I2, I3, I4) -> O {
+    // TODO: This is slightly less efficient than a Tuple4 data class.
+    val cache = mutableMapOf<List<Any?>, O>()
+    return { i1, i2, i3, i4 -> cache.getOrPut(listOf(i1, i2, i3, i4)) { this(i1, i2, i3, i4) } }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).memoize(): (I1, I2, I3, I4, I5) -> O {
+    // TODO: This is slightly less efficient than a Tuple5 data class.
+    val cache = mutableMapOf<List<Any?>, O>()
+    return { i1, i2, i3, i4, i5 -> cache.getOrPut(listOf(i1, i2, i3, i4, i5)) { this(i1, i2, i3, i4, i5) } }
+}
+
+/** Returns a locally-memoized version of this function. Two separate invocations of [memoize] will have two separate caches. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).memoize(): (I1, I2, I3, I4, I5, I6) -> O {
+    // TODO: This is slightly less efficient than a Tuple6 data class.
+    val cache = mutableMapOf<List<Any?>, O>()
+    return { i1, i2, i3, i4, i5, i6 -> cache.getOrPut(listOf(i1, i2, i3, i4, i5, i6)) { this(i1, i2, i3, i4, i5, i6) } }
+}

functional/src/commonMain/kotlin/PartialApply.kt

@@ -0,0 +1,25 @@
+package com.juul.tuulbox.functional
+
+/** Binds the argument of this function with a constant [value]. */
+public fun <I1, O> ((I1) -> O).partialApply(value: I1): () -> O =
+    { this(value) }
+
+/** Binds the first argument of this function with a constant [value]. */
+public fun <I1, I2, O> ((I1, I2) -> O).partialApply(value: I1): (I2) -> O =
+    { i2 -> this(value, i2) }
+
+/** Binds the first argument of this function with a constant [value]. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).partialApply(value: I1): (I2, I3) -> O =
+    { i2, i3 -> this(value, i2, i3) }
+
+/** Binds the first argument of this function with a constant [value]. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).partialApply(value: I1): (I2, I3, I4) -> O =
+    { i2, i3, i4 -> this(value, i2, i3, i4) }
+
+/** Binds the first argument of this function with a constant [value]. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).partialApply(value: I1): (I2, I3, I4, I5) -> O =
+    { i2, i3, i4, i5 -> this(value, i2, i3, i4, i5) }
+
+/** Binds the first argument of this function with a constant [value]. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).partialApply(value: I1): (I2, I3, I4, I5, I6) -> O =
+    { i2, i3, i4, i5, i6 -> this(value, i2, i3, i4, i5, i6) }

functional/src/commonMain/kotlin/Repeat.kt

@@ -0,0 +1,13 @@
+package com.juul.tuulbox.functional
+
+/** Returns a function that repeats the application of [this] [count] times. */
+public fun <T> ((T) -> T).repeat(count: Int): (T) -> T {
+    require(count >= 0) { "Repeat `count` must not be negative." }
+    return { initialValue ->
+        var value = initialValue
+        kotlin.repeat(count) {
+            value = this(value)
+        }
+        value
+    }
+}

functional/src/commonMain/kotlin/Reverse.kt

@@ -0,0 +1,21 @@
+package com.juul.tuulbox.functional
+
+/** Returns a function where the argument order has been reversed. */
+public fun <I1, I2, O> ((I1, I2) -> O).reverse(): (I2, I1) -> O =
+    { i2, i1 -> this(i1, i2) }
+
+/** Returns a function where the argument order has been reversed. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).reverse(): (I3, I2, I1) -> O =
+    { i3, i2, i1 -> this(i1, i2, i3) }
+
+/** Returns a function where the argument order has been reversed. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).reverse(): (I4, I3, I2, I1) -> O =
+    { i4, i3, i2, i1 -> this(i1, i2, i3, i4) }
+
+/** Returns a function where the argument order has been reversed. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).reverse(): (I5, I4, I3, I2, I1) -> O =
+    { i5, i4, i3, i2, i1 -> this(i1, i2, i3, i4, i5) }
+
+/** Returns a function where the argument order has been reversed. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).reverse(): (I6, I5, I4, I3, I2, I1) -> O =
+    { i6, i5, i4, i3, i2, i1 -> this(i1, i2, i3, i4, i5, i6) }

functional/src/commonMain/kotlin/Rotate.kt

@@ -0,0 +1,33 @@
+package com.juul.tuulbox.functional
+
+/** Returns a function where the last argument has been moved to before the first argument. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).rotate(): (I3, I1, I2) -> O =
+    { i3, i1, i2 -> this(i1, i2, i3) }
+
+/** Returns a function where the last argument has been moved to before the first argument. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).rotate(): (I4, I1, I2, I3) -> O =
+    { i4, i1, i2, i3 -> this(i1, i2, i3, i4) }
+
+/** Returns a function where the last argument has been moved to before the first argument. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).rotate(): (I5, I1, I2, I3, I4) -> O =
+    { i5, i1, i2, i3, i4 -> this(i1, i2, i3, i4, i5) }
+
+/** Returns a function where the last argument has been moved to before the first argument. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).rotate(): (I6, I1, I2, I3, I4, I5) -> O =
+    { i6, i1, i2, i3, i4, i5 -> this(i1, i2, i3, i4, i5, i6) }
+
+/** Returns a function where the first argument has been moved to after the last argument. */
+public fun <I1, I2, I3, O> ((I1, I2, I3) -> O).rotateBack(): (I2, I3, I1) -> O =
+    { i2, i3, i1 -> this(i1, i2, i3) }
+
+/** Returns a function where the first argument has been moved to after the last argument. */
+public fun <I1, I2, I3, I4, O> ((I1, I2, I3, I4) -> O).rotateBack(): (I2, I3, I4, I1) -> O =
+    { i2, i3, i4, i1 -> this(i1, i2, i3, i4) }
+
+/** Returns a function where the first argument has been moved to after the last argument. */
+public fun <I1, I2, I3, I4, I5, O> ((I1, I2, I3, I4, I5) -> O).rotateBack(): (I2, I3, I4, I5, I1) -> O =
+    { i2, i3, i4, i5, i1 -> this(i1, i2, i3, i4, i5) }
+
+/** Returns a function where the first argument has been moved to after the last argument. */
+public fun <I1, I2, I3, I4, I5, I6, O> ((I1, I2, I3, I4, I5, I6) -> O).rotateBack(): (I2, I3, I4, I5, I6, I1) -> O =
+    { i2, i3, i4, i5, i6, i1 -> this(i1, i2, i3, i4, i5, i6) }

functional/src/commonTest/kotlin/ComposeTests.kt

@@ -0,0 +1,19 @@
+package com.juul.tuulbox.functional
+
+import com.juul.tuulbox.test.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ComposeTests {
+    @Test
+    fun checkOfOrderIsCorrect() = runTest {
+        assertEquals(202, double.of(increment).invoke(100))
+        assertEquals(201, increment.of(double).invoke(100))
+    }
+
+    @Test
+    fun checkThenOrderIsCorrect() = runTest {
+        assertEquals(201, double.then(increment).invoke(100))
+        assertEquals(202, increment.then(double).invoke(100))
+    }
+}