add List

README.md

@@ -3,3 +3,39 @@
 [![Build Status](https://travis-ci.org/hexlet-components/php-pairs.svg?branch=master)](https://travis-ci.org/hexlet-components/php-pairs)
 [![Code Climate](https://codeclimate.com/github/hexlet-components/php-pairs/badges/gpa.svg)](https://codeclimate.com/github/hexlet-components/php-pairs)
 [![Issue Count](https://codeclimate.com/github/hexlet-components/php-pairs/badges/issue_count.svg)](https://codeclimate.com/github/hexlet-components/php-pairs)
+
+
+### Functions for working with Pairs
+```
+use function Pairs\cons;
+use function Pairs\car;
+use function Pairs\cdr;
+use function Pairs\toString;
+```
+
+### Functions for working with Lists
+```
+use function Lists\length;
+use function Lists\reverse;
+use function Lists\map;
+use function Lists\filter;
+use function Lists\reduce;
+```
+### example
+\# 1
+```
+$pair = cons(1, 2);
+
+$one = Pairs\car($pair); // $one = 1;
+$two = Pairs\cdr($pair) // $two = 2;
+```
+\# 2
+```
+$list = cons(1, cons(2, cons(3, cons(4, cons(5, cons(6, null))))));
+$length = length($list); // $length = 6;
+
+$filter = filter(function ($x) {
+    return $x % 2 == 0;
+}, $list);
+$result = toString($filter); \\ $result = "(2, 4, 6)";
+```

composer.json

@@ -1,22 +1,23 @@
 {
-  "name": "hexlet\\pairs",
-  "description": "",
-  "license": "MIT",
-  "keywords": ["pairs"],
-  "authors": [
-    {
-      "name": "Kirill Mokevnin",
-      "email": "[email protected]"
+    "name": "hexlet\\pairs",
+    "description": "",
+    "license": "MIT",
+    "keywords": ["pairs"],
+    "authors": [
+        {
+            "name": "Kirill Mokevnin",
+            "email": "[email protected]"
+        }
+    ],
+    "require": {},
+    "require-dev": {
+        "phpunit/phpunit": "*",
+        "squizlabs/php_codesniffer": "2.*"
+    },
+    "autoload": {
+        "files": [
+            "src/Pairs.php",
+            "src/Lists.php"
+        ]
     }
-  ],
-  "require": {},
-  "require-dev": {
-    "phpunit/phpunit": "*",
-    "squizlabs/php_codesniffer": "2.*"
-  },
-  "autoload": {
-    "files": [
-      "src/Pairs.php"
-    ]
-  }
 }

phpunit.xml.dist

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<phpunit backupGlobals="false"
+         backupStaticAttributes="false"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false"
+         syntaxCheck="false"
+         bootstrap="vendor/autoload.php"
+>
+  <testsuites>
+    <testsuite name="Test Suite">
+      <directory>./tests/</directory>
+    </testsuite>
+  </testsuites>
+</phpunit>

src/Lists.php

@@ -0,0 +1,107 @@
+<?php
+
+namespace Lists;
+
+use function Pairs\cons;
+use function Pairs\car;
+use function Pairs\cdr;
+use function Pairs\toString;
+
+/**
+ * Applies callable function $func to list $list
+ * @param  callable $func function
+ * @param  callable $list list
+ * @return result list
+ */
+function map(callable $func, callable $list)
+{
+    $map = function ($items, $acc) use (&$map, $func) {
+        if (is_null($items)) {
+            return reverse($acc);
+        }
+        return $map(cdr($items), cons($func(car($items)), $acc));
+    };
+
+    return $map($list, null);
+}
+
+/**
+ * Filters list $list using callable function $func
+ * @param  callable $func function
+ * @param  callable $list list
+ * @return result list
+ */
+function filter(callable $func, callable $list)
+{
+    $map = function ($func, $items) use (&$map) {
+        if ($items === null) {
+            return null;
+        } else {
+            $curr = car($items);
+            $rest = $map($func, cdr($items));
+            // filter
+            return $func($curr) ? cons($curr, $rest) : $rest;
+        }
+    };
+
+    return $map($func, $list);
+}
+
+/**
+ * Collapses the list $list using callable function $func
+ * @param  callable $func function
+ * @param  callable $list list
+ * @param  mixed   $acc
+ * @return result
+ */
+function reduce(callable $func, callable $list, $acc = null)
+{
+    $iter = function ($items, $acc) use (&$iter, $func) {
+        return is_null($items) ? $acc : $iter(cdr($items), $func(car($items), $acc));
+    };
+
+    return $iter($list, $acc);
+}
+
+/**
+ * Concatenates two lists
+ * @param  pair $list1
+ * @param  pair $list2
+ * @return new list
+ */
+function append(callable $list1, callable $list2)
+{
+    if ($list1 === null) {
+        return $list2;
+    } else {
+        return cons(car($list1), append(cdr($list1), $list2));
+    }
+}
+
+/**
+ * Reverse list $list
+ * @param  callable $list list
+ * @return result
+ */
+function reverse(callable $list)
+{
+    $iter = function ($items, $acc) use (&$iter) {
+        return is_null($items) ? $acc : $iter(cdr($items), cons(car($items), $acc));
+    };
+
+    return $iter($list, null);
+}
+
+/**
+ * Returns length of list
+ * @param  callable $list list
+ * @return integer  length
+ */
+function length($list)
+{
+    if ($list === null || !is_callable($list)) {
+        return 0;
+    } else {
+        return 1 + length(cdr($list));
+    }
+}

src/Pairs.php

@@ -33,7 +33,7 @@ function toString($list)
     $arr = [];
     $iter = function ($items) use (&$arr, &$iter) {
         if ($items != null) {
-            $arr[] = listToString(car($items));
+            $arr[] = toString(car($items));
             $iter(cdr($items));
         }
 

tests/ListsTest.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Pairs\tests;
+
+use function Pairs\cons;
+use function Pairs\car;
+use function Pairs\cdr;
+use function Pairs\toString;
+use function Lists\length;
+use function Lists\reverse;
+use function Lists\map;
+use function Lists\filter;
+use function Lists\reduce;
+
+class ListsTest extends \PHPUnit_Framework_TestCase
+{
+
+    public function testLength()
+    {
+        $list = cons(1, cons(2, cons(3, null)));
+        $this->assertEquals(3, length($list));
+    }
+
+    public function testReverse()
+    {
+        $list = cons(1, cons(2, cons(3, null)));
+        $expected = toString(cons(3, cons(2, cons(1, null))));
+        $this->assertEquals($expected, toString(reverse($list)));
+    }
+
+    public function testMap()
+    {
+        $list = cons(1, cons(2, cons(3, null)));
+        $expected = toString(cons(3, cons(4, cons(5, null))));
+        $map = map(function ($x) {
+            return $x + 2;
+        }, $list);
+        $this->assertEquals($expected, toString($map));
+    }
+
+    public function testFilter()
+    {
+        $list = cons(2, cons(3, cons(4, null)));
+        $expected = toString(cons(2, cons(4, null)));
+        $filter = filter(function ($x) {
+            return $x % 2 == 0;
+        }, $list);
+
+        $this->assertEquals(2, length($filter));
+        $this->assertEquals($expected, toString($filter));
+    }
+
+    public function testReduce()
+    {
+        $list = cons(1, cons(2, cons(3, null)));
+        $expected = 6;
+        $map = reduce(function ($x, $acc) {
+            return $x + $acc;
+        }, $list, 0);
+        $this->assertEquals($expected, $map);
+    }
+}