From 01a47fab453136ba847874f53e5b5dfeb44c2a70 Mon Sep 17 00:00:00 2001 From: Alexander Nozik Date: Tue, 10 Oct 2023 08:04:59 +0300 Subject: [PATCH] add idioms notebook --- Idioms.ipynb | 2145 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 2145 insertions(+) create mode 100644 Idioms.ipynb diff --git a/Idioms.ipynb b/Idioms.ipynb new file mode 100644 index 0000000..9cda1c6 --- /dev/null +++ b/Idioms.ipynb @@ -0,0 +1,2145 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "source": [ + "Original repository: https://code.mipt.ru/SPC/education/ks-materials" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "e5U9H2j8YPqeTklThKWtLy", + "type": "MD", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "xIF3Up82GVsiV1Ceze6Si3", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 1, String interpolation\n", + "\n", + "Interpolated string allows constructing string fast" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "LVICJjSl3FQ9CWiBWDaNlp", + "type": "MD", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "xIF3Up82GVsiV1Ceze6Si3", + "relativeY": 6 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "println(\"This is a plain string\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "FFW0GaV6uhemvZxlpnjpFL", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "ypTKLK2KvAZfnMbTgaVqNK", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "val arg = \"Interpolated\"\n", + "println(\"This is an $arg string\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "ZsQ4OOCMRSSkquucGThKYh", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "qyGLHGsLl6mRCaOjpZBTD3", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "val number = 1\n", + "println(\"This is an $arg string number ${number + 1}\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "7V2Dsj0FwQaSqFJcYcWsz9", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "7tql3kbsQ9JIbbEfghi48B", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "println(\"This is a string with \\$\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "hm9iYlWj1B2S0469GtxDrf", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "BQz86nEWOj77fxXQ8iS47U", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "println(\"\"\"\n", + " This is a \n", + " multi\n", + " line\n", + " raw\n", + " string\n", + "\"\"\".trimIndent())" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "h6GsBoqNfrx3k1edy3hjKZ", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "RTl3zV3tStzlLoIHSvEZiV", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "println(\"\"\"This is a raw string number ${number+1} with \\ and ${'$'} \"\"\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "KDL3D9lOVn6vX3iTAY50gb", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "xmBQdVRhRGLsw0t87vxQW7", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 2, val VS var\n", + "\n", + "`val` means read-only property\n", + "\n", + "`var` means writable property\n", + "\n", + "Unnecessary use of `var` is not recommended.\n", + "\n", + "**NOTE:** In performance critical cases, explicit cycles are better, but mutable state should be encapsulated." + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "mz5BUTYWXHfIAjGOyinhqi", + "type": "MD", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "MpSiMp90k75zOtoELK5XSp", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "/* Not recommended */\n", + "var counter = 0\n", + "for(i in 0..20){\n", + " counter += i\n", + "}\n", + "counter" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "KyyAj8GiWSE3ZOFi2Ct8pD", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 0 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "/* recommended */\n", + "val sum = (0..20).sum()\n", + "sum" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "NKkj9bAwRFxueaMe7iiov6", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 6 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "val intArray: IntArray = IntArray(21) { it }\n", + "intArray.sum()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "icUKtPZGuhHjb95pFh77cl", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 12 + } + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 3 top level functions" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "PSmFAqLCw6ko0q3IWbHk4x", + "type": "MD", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 18 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * Functions could be defined everywhere in kotlin code. This is a so-called top-level function.\n", + " */\n", + "fun doSomething(){\n", + " println(\"I did it\")\n", + "}\n", + "\n", + "doSomething()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "pKnOC6YRLvZ7Xj6SWth2bP", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 24 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "object AnObject{\n", + " /**\n", + " * This is a member-function\n", + " */\n", + " fun doSomethingInAnObject(){\n", + " println(\"I did it in an object\")\n", + " }\n", + "}\n", + "\n", + "AnObject.doSomethingInAnObject()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "z1PRFmypCJbpbsxEaiVol5", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 30 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "fun doSomethingSpecial(){\n", + " val special = \"special\"\n", + " /**\n", + " * This one is inside another function\n", + " */\n", + " fun doSomethingInside(){\n", + " println(\"I did $special inside another function\")\n", + " }\n", + " doSomethingInside()\n", + "}\n", + "\n", + "doSomethingSpecial()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "w8hub7Az3lxh78KXeq7Cpv", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 36 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "fun returnFunction(): (String) -> Unit{\n", + " fun printStringWithPrefix(str: String){\n", + " println(\"Prefixed: $str\")\n", + " }\n", + " return ::printStringWithPrefix\n", + " // return { println(\"Prefixed: $it\") }\n", + "}\n", + "\n", + "returnFunction()(\"Haskel, Boo!\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "QxeCTOYkFSZi5tvWoUvRwU", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 42 + } + } + } + }, + { + "cell_type": "markdown", + "source": [], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "0zwWQ2uPSUrlAoyy1k0GlZ", + "type": "MD", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 48 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "//idiom 3 - Unit\n", + "fun returnUnit(): Unit{\n", + " // no return statement `Unit` is returned implicitly\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "UxEwPmJN8zFnMxBiL1Kd2W", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 54 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "//idiom 4 - default parameters\n", + "fun doSomethingWithDefault(a: Int = 0, b: String = \"\"): String {\n", + " return \"A string with a == $a and b == \\\"$b\\\"\"\n", + "}\n", + "\n", + "doSomethingWithDefault(4, b = \"fff\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "Pds7b8enkYPmA9KAaO20zI", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 60 + } + } + } + }, + { + "cell_type": "code", + "source": [ + "//idiom 5 - function body shortcut\n", + "fun theSameAsBefore(a: Int = 0, b: String = \"\"): String = \"A string with a == $a and b == $b\"" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "wEpzn9oKJBKKsBDGytj92U", + "type": "CODE", + "hide_input_from_viewers": false, + "hide_output_from_viewers": false, + "report_properties": { + "rowId": "vqa5BMfmP7oZwt8sdVLKi8", + "relativeY": 66 + } + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 6" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "qBWuWasNK9nrp0iqoE1ZPA", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "//Interfaces and objects\n", + "\n", + "interface AnInterface {\n", + " val a: Int\n", + " get() = 4\n", + " // set(value){\n", + " // println(value)\n", + " // }\n", + " fun doSomething()\n", + "}\n", + "\n", + "class AClass(override val a: Int) : AnInterface {\n", + " override fun doSomething() = TODO()\n", + "}\n", + "\n", + "/**\n", + " * A singleton (object) is a type (class) which have only one instance\n", + " */\n", + "object AnObject : AnInterface {\n", + " override fun doSomething(): Unit = TODO(\"Not yet implemented\")\n", + "}\n", + "\n", + "/**\n", + "* Creating an instance\n", + "*/\n", + "val instance = AClass(3)\n", + "\n", + "/**\n", + "* Using singleton reference without constructor invocation\n", + "*/\n", + "val obj: AnInterface = AnObject\n", + "\n", + "/**\n", + "* Anonymous object\n", + "*/\n", + "val anonymous = object : AnInterface {\n", + " override fun doSomething(): Unit = TODO(\"Not yet implemented\")\n", + "}\n", + "\n", + "/**\n", + "* The one that should not be named\n", + "*/\n", + "val voldemort = object {\n", + " fun doSomething(): Unit = TODO()\n", + "}\n", + "\n", + "voldemort.doSomething()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "aW9cBvDwbbUsi2CBRrXDPB", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 7\n", + "Runtime type dispatch" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "GI03Lj2Li76ORUHS53nTIx", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * Matching by type\n", + " */\n", + "fun checkType(arg: Any): Unit = when(arg){\n", + " is String -> println(\"I am a String\")\n", + " is Int -> println(\"I am an Int\")\n", + " is Double -> println(\"I am a Double\")\n", + " // 2==2 -> println(\"Wat?\")\n", + " else -> println(\"I don't know who am I?\")\n", + "}\n", + "\n", + "fun checkType2(arg: Any): Unit = when{\n", + " arg is String -> println(\"I am a String\")\n", + " arg is Int -> println(\"I am an Int\")\n", + " arg is Double -> println(\"I am a Double\")\n", + " 2==2 -> println(\"Wat?\")\n", + " else -> println(\"I don't know who am I?\")\n", + "}\n", + "\n", + "checkType2(true)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "tJXxwCbGkVrfybQ0WZBOtt", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "88QaLyOEuKme4fa1GZpBRL", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 8" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "vOQiEaU7CW3kIB3K4W2hEK", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "class SimpleClass(val a: Int, val b: Double, c: Double)\n", + "\n", + "\n", + "data class DataClass(val a: Int, val b: Double) {\n", + " val c get() = b + 1\n", + "}\n", + "\n", + "val simple = SimpleClass(1, 2.0, 3.0)\n", + "\n", + "println(simple)\n", + "\n", + "val data = DataClass(2, 2.0)\n", + "val copy = data.copy(b = 22.2)\n", + "println(copy)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "B7unRz7w7U8OhXejJeFspj", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 9" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "cXeTiH13nXoPhTXZLkRnLj", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * The declaration if valid because [TODO] returns Nothing\n", + " */\n", + "fun getSomething(): Int? = TODO()\n", + "\n", + "fun findSomething(): Int {\n", + " // early return is valid because `return` operator result is Nothing\n", + " val found = getSomething() ?: return 2\n", + " return found + 2\n", + "}\n", + "\n", + "fun checkCondition(): Int {\n", + " fun conditionSatisfied() = false\n", + "\n", + " return if (conditionSatisfied()) {\n", + " 1\n", + " } else {\n", + " //error is Nothing\n", + " error(\"Condition is not satisfied\")\n", + " }\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "h11q8FWGKYIcuFOnFOLmBl", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "clBRddjfvKnMe2EMSmDhLd", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * idiom 10\n", + " * Nullable truth.\n", + " */\n", + "fun idiom10() {\n", + " class A(val b: Boolean?)\n", + "\n", + " val a: A? = A(null) // Compilator warning here\n", + " //use\n", + " a?.b == true\n", + " //instead of\n", + " a?.b ?: false\n", + "\n", + " // The old way\n", + " val res = if (a == null) {\n", + " false\n", + " } else {\n", + " if (a.b == null) {\n", + " false\n", + " } else {\n", + " a.b\n", + " }\n", + " }\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "5BN3u1gHkSamtLIJiQicsV", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * Dart-like (?=) nullable assignment\n", + " */\n", + "fun idiom11() {\n", + " var x: String? = null\n", + " x = x ?: \"Hello\"\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "di2EXkn35CFEja9KMK1Ur5", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * Safe call and elvis operator\n", + " */\n", + "fun idiom12() {\n", + " val files = File(\"Test\").listFiles()\n", + " println(files?.size ?: \"empty\")\n", + "}\n", + "idiom12()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "v4cP31zyrmBkHP7lnYZWN0", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 13" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "u8kNpLP2GJ8TLRgyk3kI4Z", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "fun printNotNull(any: Any) = println(any)\n", + "\n", + "// printNotNull(null) does not work\n", + "\n", + "val value: Int? = 2\n", + "//val value: Int? by lazy{ 2 }\n", + "\n", + "//printNotNull(value) // Error\n", + "if (value != null) {\n", + " //not guaranteed to work with mutable variable\n", + " printNotNull(value)\n", + "}\n", + "\n", + "var value1: Int? = 2\n", + "\n", + "// Safe call here\n", + "value1?.let {\n", + " printNotNull(it) // execute this block if not null\n", + " //printNotNull(value1) // value is not null here\n", + "}\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "hGZ9h4H8TaYZefCkAmP3Gd", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 14: Extension functions" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "aC24azwiFpZfA2v3umRb7p", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * Extension function on a String. It is not monkey-patching.\n", + " */\n", + "fun String.countOs(): Int = count { it == 'о' } // implicit this points to String\n", + "\n", + "fun Int.printMe() = println(this) // explicit this\n", + "\n", + "\"вылысыпыдыстычка\".countOs().printMe()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "li65OumXRClbEIwURW9DEE", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "infix fun > ClosedRange.intersect(other: ClosedRange): ClosedRange?{\n", + " val start = maxOf(this.start, other.start)\n", + " val end = minOf(this.endInclusive, other.endInclusive)\n", + " return if(end>=start) start..end else null\n", + "}\n", + "\n", + "0..8 intersect 6..12" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "cyD7D8tmZJex8pJ3NsufHN", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "15" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "pJTxzy4MfR710OowVbvf6s", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * Extension property (must be virtual)\n", + " */\n", + "val List.odd get() = filter { it % 2 == 1 }\n", + "\n", + "/**\n", + " * Extension variable (also must be virtual)\n", + " */\n", + "var Array.second: Int\n", + " get() = this[1]\n", + " set(value) {\n", + " this[1] = value\n", + " }\n", + "\n", + "\n", + "val array = Array(5){it}\n", + "array.second = 9\n", + "array" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "L7qpVNVtW0Fh6dMX4pR3il", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Scope functions (run, with, let)" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "Ziq72FmnnYUYPMy4CamsQ0", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "object AClass{\n", + " val a = \"a\"\n", + " val b = \"b\"\n", + " val c = \"c\"\n", + "}\n", + "\n", + "fun getAClass(): AClass? = null\n", + "\n", + "/**\n", + " * [with]/[run]/[let] are used to create a scope with given argument or receiver\n", + " */\n", + "\n", + "\n", + "// Simple print of AClass\n", + "println(\"a = ${AClass.a}, b = ${AClass.b}, c = ${AClass.c}\")\n", + "\n", + "// Using `with`\n", + "val res = with(AClass){\n", + " // AClass type is the receiver in this scope\n", + " println(\"a = $a, b = $b, c = $c\")\n", + " return@with \"some value\"\n", + "}\n", + "\n", + "res" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "7wtXhm3FeLejbPp7NEWiz2", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "//using `run`\n", + "getAClass()?.run {\n", + " // the same as above\n", + " println(\"a = $a, b= $b, c = $c\")\n", + "}\n", + "\n", + "//Using `let` to compose result. Not recommended using without a need\n", + "val letResult = getAClass()?.let { arg ->\n", + " arg.c + arg.a\n", + "}\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "aJGJ3ukmhCchnZwJEzLV3K", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Scope functions (also, apply)" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "r6VfHIkDTBDCIotqNCslOH", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "class Rectangle{\n", + " var length: Number = 0\n", + " var breadth: Number=0\n", + " var color: Int = 0xffffff\n", + "}\n", + "\n", + "/**\n", + " * Using apply/also to add a finalizing action\n", + " */\n", + "var i = 2\n", + "\n", + "/**\n", + "* [also] block does not affect the result\n", + "*/\n", + "fun getAndIncrement() = i.also { i += 1 }\n", + "\n", + "println(getAndIncrement())\n", + "println(i)\n", + "\n", + "/**\n", + " * Configure properties of an object (apply)\n", + " * https://kotlinlang.org/docs/idioms.html#configure-properties-of-an-object-apply\n", + " */\n", + "val myRectangle = Rectangle().apply {\n", + " length = 4\n", + " breadth = 5\n", + " color = 0xFAFAFA\n", + "}\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "c0kY56DJne2lbwGShOgur6", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "class A() {\n", + " inner class B{\n", + " fun doSomething(){\n", + " println(this)\n", + " println(this@A)\n", + " }\n", + " }\n", + "}\n", + "A().B().doSomething()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "DwdqqVgNEtyUygmp4Hc7Bp", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "mbxaxoN1wrwBpdl5OeDcKf", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 18 lists" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "lMgnCCxkRhs62cgTQN5eDK", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * Lists and mutable lists\n", + " */\n", + "\n", + "\n", + "/**\n", + " * This method creates a read-only list of strings. One should note that the type of the list is not specified\n", + " */\n", + "val list = listOf(\"a\", \"b\", \"c\")\n", + "\n", + "println(list[0])\n", + "println(list.get(1))\n", + "println(list.getOrNull(4) ?: \"nothing\")" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "pP9PTSy6IXeTC6HITFtBoR", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + "* This one creates a mutable list\n", + "*/\n", + "val mutableList: MutableList = mutableListOf(\"a\", \"b\", \"c\")\n", + "mutableList[2] = \"d\"\n", + "mutableList.add(\"e\")\n", + "mutableList += \"f\"\n", + "mutableList" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "Kx565m7VjuF2RncqW7gw2i", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * This one creates a mutable ArrayList.\n", + " */\n", + "val arrayList: ArrayList = arrayListOf(\"a\", \"b\", \"c\")\n", + "\n", + "//Danger zone\n", + "\n", + "val newList: List = list + \"f\" + mutableList\n", + "\n", + "println(newList)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "qSaaZGyHiH9dsL4dtQ8UyE", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "//Bonus\n", + "\n", + "val lambdaList = List(3){ it.toString() }\n", + "println(lambdaList)\n", + "\n", + "\n", + "val builderList = buildList{\n", + " add(2)\n", + " add(8)\n", + " remove(8)\n", + "}\n", + "builderList" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "JPSYaCAgOZRveNdFPO15SG", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "// val sequentialList = List(20){it}\n", + "// sequentialList.zipWithNext{ l, r -> r - l }.forEach{println(it)}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "fQBhhTBHCdc9JkWiMZ6uEh", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * idiom 19\n", + " * Use shortcut function to provide default values\n", + " */\n", + "fun doSomething(additionalArguments: List = emptyList()){\n", + " TODO()\n", + " emptyArray()\n", + " emptySet()\n", + " emptyMap()\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "F5RQ5108YJe3pzfN0eAWwm", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 20" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "TSOQN81tDBKM3Z3oUOHGom", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "val map = mutableMapOf(\n", + " \"key\" to \"a\",\n", + " \"key2\" to \"b\",\n", + ")\n", + "\n", + "//The map could be accessed via indexing operation\n", + "println(map[\"key\"])\n", + "map[\"key\"] = \"fff\"" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "cZd2JPB72uAfnx1o8AYjOs", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "//val entry: MutableMap.MutableEntry = map.iterator().next()\n", + "\n", + "/**\n", + " * The destructuring declaration for maps and other objects that support `operator fun componentN`\n", + " */\n", + "for ((k, v) in map) {\n", + "//val (k, v) = entry\n", + "// val k = entry.component1()\n", + "// val v = entry.component2()\n", + " println(\"$k -> $v\")\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "hRuaLFdpTsdnt7lYKL2nbN", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "map.forEach { (k, v) -> println(\"$k -> $v\")}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "s1Q65aNWb9YNBZOgxmjotW", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "val (a, b) = Pair(1, 2)\n", + "\n", + "val coord = doubleArrayOf(0.0, 1.0, 2.0)\n", + "\n", + "val (x,y,z) = coord\n", + "\n", + "data class Coordinate(val x: Double, val y: Int)\n", + "\n", + "val (x1, y1) = Coordinate(1.0,2)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "t8YITxVsoTt7o9KnnOvO0Z", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 22 Mutable type access decorator" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "Ec2mbBaydQnVsjaiThy2rn", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "class AClassWithList{\n", + " var b: Double = 2.0\n", + " private set\n", + "\n", + " init{\n", + " b = 5.0\n", + " }\n", + "\n", + " private val _list: MutableList = ArrayList()\n", + " val list: List get() = _list\n", + "}\n", + "\n", + "\n", + "\n", + "val obj = AClassWithList()\n", + "\n", + "// obj.b = 10.0 //error\n", + "obj.list\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "H8VTPpGlV0VwsHL4Q8lJF9", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 23" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "GKoCVcgdnSYPjsNCAJIkBB", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "val emailsList = emptyList()\n", + "\n", + "// When used directly infix in operator checks if the element is contained in a collection\n", + "//using `operator fun contains`\n", + "\n", + "if (\"john@example.com\" in emailsList) {\n", + " println(\"is in list\")\n", + "}\n", + "\n", + "if (\"jane@example.com\" !in emailsList) {\n", + " println(\"not in list\")\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "4mh1Lg6g8OWEIC1Qjgp9tN", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "\n", + "class DateRange(val start: Instant, val end: Instant)\n", + "\n", + "operator fun DateRange.contains(value: Instant): Boolean = value > start && value < end\n", + "\n", + "\n", + "println(Instant.now() in DateRange(Instant.EPOCH, Instant.MAX))" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "1N4A00CAksn2nVg57DRKnp", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "// Another (different) use of `in` is iteration over range or collection using\n", + "// using `operator fun iterator`\n", + "\n", + "for (i in 1..100) {\n", + " println(i)\n", + "} // closed range: includes 100\n", + "\n", + "(1..100).forEach { i ->\n", + " println(i)\n", + "} //the same, but with boxing\n", + "\n", + "for (i in 1 until 100) {\n", + " println(i)\n", + "} // half-open range: does not include 100\n", + "\n", + "for (x in 2..10 step 2) {\n", + " println(x)\n", + "}\n", + "for (x in 10 downTo 1) {\n", + " println(x)\n", + "}\n", + "\n", + "infix fun ClosedRange.step(step: Double): Sequence {\n", + " //TODO check arguments\n", + " var current = start\n", + " return sequence {\n", + " do {\n", + " yield(current)\n", + " current += step\n", + " } while (current <= endInclusive)\n", + " }\n", + "}\n", + "\n", + "for (x in 0.0..10.0 step 0.5){\n", + " println(x)\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "hwJfUD7H5mDtjStAsGppk7", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 25 default arguments" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "s5b86yOyyGrX0uWGB5xM8o", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "fun integrate(\n", + " from: Double = 0.0,\n", + " to: Double = 1.0,\n", + " step: Double = 0.01,\n", + " function: (Double) -> Double,\n", + "): Double {\n", + " require(to > from)\n", + " require(step > 0)\n", + " var sum = 0.0\n", + " var pos = from\n", + " while (pos < to) {\n", + " sum += function(pos)\n", + " pos += step\n", + " }\n", + " return sum*step\n", + "}\n", + "\n", + "integrate { x ->\n", + " x * x + 2 * x + 1\n", + "}\n", + "integrate(0.0, PI) { sin(it) }\n", + "integrate(0.0, step = 0.02, to = PI) { sin(it) }\n", + "//integrate(0.0, step = 0.02, PI) { sin(it) }" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "K7VpwS850ZiYXJlKx8oujo", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 26 map-reduce" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "IsJiqd43JpY7BnZTeHNU4M", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "val list: List = listOf(1, 2, 3, 4, 5, 6)\n", + "\n", + "val result = list\n", + " //.stream().parallel()\n", + " //.asSequence()\n", + " .filter { it % 2 == 0 } //select even numbers\n", + " .map { it * it } // get square of each element\n", + " //.onEach { println(it) }\n", + " //.sumOf { it } //use one of reduce operations\n", + " .reduce { acc: Int, i: Int -> acc + i }\n", + "\n", + "result" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "KKT62bidVYF8I147heptAS", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 28 Wrap mutable logic" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "k1eHOcIZbnHDJ8g7ZusArx", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "val list = buildList {\n", + " repeat(10){\n", + " add(it)\n", + " }\n", + "}\n", + "println(list)\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "pJfVynao7enb7Q07lJRGRl", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 29 resource usage" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "ovz77VglMntuRrJ1uMtSEG", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "\n", + "\n", + "val stream = Files.newInputStream(Paths.get(\"file.txt\"))\n", + "// The resource is automatically closed when leaving the scope\n", + "stream.bufferedReader().use { reader ->\n", + " println(reader.readText())\n", + "}" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "XIX7lDFJ0UiyiJAY4c3Oby", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 30 Factory as parameter and companion factories" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "MizpHzkgkV5TzoM9HFS2zM", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "interface Factory {\n", + " fun build(str: String): T\n", + "}\n", + "\n", + "class IntContainer(val arg: Int) {\n", + " \n", + " companion object : Factory {\n", + " override fun build(str: String) = IntContainer(str.toInt())\n", + " }\n", + "}\n", + "\n", + "class DoubleContainer(val arg: Double) {\n", + " \n", + " companion object : Factory {\n", + " override fun build(str: String) = DoubleContainer(str.toDouble())\n", + " }\n", + "}\n", + "\n", + "fun buildContainer(str: String, factory: Factory): T = factory.build(str)\n", + "\n", + "\n", + "buildContainer(\"22\", IntContainer)\n" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "TAnNAjBb2Rc1RRTTICVuZg", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 31 initialization" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "l8Zp9Da24jvCFJd28sDNFj", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "open class Bad{\n", + " val value: Int\n", + "\n", + " init {\n", + " value = requestValue()\n", + " }\n", + "\n", + " open fun requestValue(): Int {\n", + " doSomethingElse()\n", + " return 2\n", + " }\n", + "\n", + " private fun doSomethingElse(){\n", + " println(value)\n", + " }\n", + "}\n", + "\n", + "Bad()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "xZWJjxthdbhrVOMYfed6UV", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "\n", + "//Factory functions are preferred to the initialization logic\n", + "\n", + "data class Good internal constructor(val value: Int){\n", + " init {\n", + " //Initialization block is there to check arguments\n", + " require(value >= 0)\n", + " }\n", + "\n", + " companion object\n", + "}\n", + "\n", + "fun requestValue(): Int = TODO()\n", + "\n", + "// This is the factory-function\n", + "fun Good() = Good(requestValue())\n", + "\n", + "\n", + "// additional constructor-like builders could be added to the companion\n", + "\n", + "@OptIn(ExperimentalUnsignedTypes::class)\n", + "fun Good.Companion.build(value: UInt) = Good(value.toInt())\n", + "\n", + "Good.build(32U)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "2oRxs51NNlsoJD7UIx3exC", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 32 Delegates" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "jvl9An4EkBkWd9B1JX4ju9", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "class ClassWithALazyProperty{\n", + " //Use lazy delegate for something that should be calculated ones on first call\n", + " val lazyValue by lazy {\n", + " //Do dome heavy logic here\n", + " println(\"Initialized\")\n", + " 22\n", + " }\n", + "\n", + " val getterValue:Int get(){\n", + " println(\"got\")\n", + " return 33\n", + " }\n", + "}\n", + "val lazyClass = ClassWithALazyProperty()\n", + "lazyClass.lazyValue\n", + "lazyClass.lazyValue\n", + "lazyClass.getterValue\n", + "lazyClass.getterValue" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "CqN0VKctxRWd4N4RrKC90M", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "//Using other delegates\n", + "val map = mapOf(\"a\" to 1, \"b\" to 2)\n", + "\n", + "val a: Int by map\n", + "\n", + "println(a)" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "TYw8wCso8aGvqvd2XviRcH", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 33 Inline functions" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "OkBtMlEkvfaglVXzlzq5dU", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * Definition of inline function\n", + " */\n", + "inline fun List.forEachOdd(block: (Int) -> Unit) = forEach {\n", + " if (it % 2 == 1) block(it)\n", + "}\n", + "\n", + "\n", + "/**\n", + " * The demonstration of use of inline [forEach] function with non-local return\n", + " */\n", + "fun foo() {\n", + " listOf(1, 2, 3, 4, 5).forEach {\n", + " if (it == 3) return // non-local return directly to the caller of foo()\n", + " print(\"$it, \")\n", + " }\n", + " println(\"this point is unreachable\")\n", + "}\n", + "foo()" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "kz2Dq5cDNhfbfgI6mXv5yU", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "\n", + "/**\n", + " * Using inline function for type reification during the compile time\n", + " */\n", + "inline fun List.prettyPrint() = forEach {\n", + " when (T::class) {\n", + " Double::class -> println(\"Double: ${it as Double}\")\n", + " Int::class -> println(\"Int: ${it as Int}\")\n", + " else -> it.toString()\n", + " }\n", + "}\n", + "\n", + "inline fun prettyPrintOne(arg: T) = listOf(arg).prettyPrint()\n", + "\n", + "/**\n", + " * **WARNING** inline functions are an advanced feature and should be used only for\n", + " * reification or non-local return\n", + " * NOT for optimization.\n", + " */" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "drMX3vZ5PBfpBXhCZM1zc5", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "markdown", + "source": [ + "## Idiom 34 Collections and boxing" + ], + "attachments": {}, + "metadata": { + "datalore": { + "node_id": "6I3SqcgBGWPqpKZRhNDfAM", + "type": "MD", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [ + "/**\n", + " * Values are boxed. Each call is indirect\n", + " */\n", + "val list: List = List(20) { it.toDouble() }\n", + "\n", + "/**\n", + " * Still boxed\n", + " */\n", + "val genericArray: Array = Array(20) { it.toDouble() }\n", + "\n", + "/**\n", + " * Non-boxed\n", + " */\n", + "val specializedArray: DoubleArray = DoubleArray(20) { it.toDouble() }" + ], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "ieHZ3zzSufTtNWM11pIuh1", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + }, + { + "cell_type": "code", + "source": [], + "execution_count": null, + "outputs": [], + "metadata": { + "datalore": { + "node_id": "L6tcPZIURXXDefw83NWlH8", + "type": "CODE", + "hide_input_from_viewers": true, + "hide_output_from_viewers": true + } + } + } + ], + "metadata": { + "kernelspec": { + "display_name": "Kotlin", + "language": "kotlin", + "name": "kotlin" + }, + "datalore": { + "computation_mode": "JUPYTER", + "package_manager": "pip", + "base_environment": "default", + "packages": [], + "report_row_ids": [ + "xIF3Up82GVsiV1Ceze6Si3", + "ypTKLK2KvAZfnMbTgaVqNK", + "qyGLHGsLl6mRCaOjpZBTD3", + "7tql3kbsQ9JIbbEfghi48B", + "BQz86nEWOj77fxXQ8iS47U", + "RTl3zV3tStzlLoIHSvEZiV", + "xmBQdVRhRGLsw0t87vxQW7", + "MpSiMp90k75zOtoELK5XSp", + "vqa5BMfmP7oZwt8sdVLKi8" + ], + "version": 3 + } + }, + "nbformat": 4, + "nbformat_minor": 4 +}