public function test_it_should_return_new_map()
{
$collection = Listt::of([['id' => 1, 'name' => 'One'], ['id' => 2, 'name' => 'Two'], ['id' => 3, 'name' => 'Three']]);
$result = $collection->map(function ($a) {
return $a['id'] + 1;
});
$this->assertEquals(Listt::of([2, 3, 4]), $result);
}
public function test_foldr()
{
$list = Listt::of([1, 2, 3, 4]);
$result = f\foldr(function ($accumulator, $value) {
return f\concatM($accumulator, Listt::of([$value + 1]));
}, Listt::of([]), $list);
$this->assertEquals($result, Listt::of([5, 4, 3, 2]));
}
public function test_it_should_sum_all_from_one_list_with_single_element()
{
// sum <$> [1, 2] <*> [4, 5]
$sum = f\curryN(2, 'example\\sum');
$a = Listt::of([1, 2]);
$b = Listt::of([4, 5]);
$result = f\map($sum, $a)->ap($b);
$this->assertEquals(Listt::of([5, 6, 6, 7]), $result);
}
public function test_it_should_combine_two_lists()
{
// [1,2] >>= \n -> ['a','b'] >>= \ch -> return (n,ch) == [(1,'a'),(1,'b'),(2,'a'),(2,'b')]
$result = Listt::of([1, 2])->bind(function ($n) {
return Listt::of(['a', 'b'])->bind(function ($x) use($n) {
return [[$n, $x]];
});
});
$this->assertEquals(Listt::of([[1, 'a'], [1, 'b'], [2, 'a'], [2, 'b']]), $result);
}
/**
* @dataProvider provideData
*/
public function test_it_should_extract_elements_which_exists_alternative_solution($data)
{
// $get :: String a -> Maybe [b] -> Maybe b
$get = function ($key) {
return f\bind(function ($array) use($key) {
return isset($array[$key]) ? m\just($array[$key]) : m\nothing();
});
};
$result = Listt::of($data)->map(Maybe\maybeNull)->bind($get('meta'))->bind($get('images'))->bind($get(0));
$this->assertEquals(Listt::of([m\just('//first.jpg'), m\just('//third.jpg'), m\nothing()]), $result);
}
public function test_it_should_apply_every_function_in_collection_with_every_item_in_second()
{
$collectionA = Listt::of([function ($a) {
return 3 + $a;
}, function ($a) {
return 4 + $a;
}]);
$collectionB = Listt::of([1, 2]);
$result = $collectionA->ap($collectionB);
$this->assertInstanceOf(Listt::class, $result);
$this->assertEquals(Listt::of([4, 5, 5, 6]), $result);
}
/**
* foldr :: Foldable t => (a -> b -> b) -> b -> t a -> b
*
* Foldr is expresed by foldl (reduce) so it loose some properties.
* For more reading please read this article https://wiki.haskell.org/Foldl_as_foldr
*
* @param callable $callable Binary function ($value, $accumulator)
* @param mixed $accumulator
* @param Foldable $foldable
*
* @return mixed
*/
function foldr(callable $callable, $accumulator = null, Foldable $foldable = null)
{
return call_user_func_array(curryN(3, function (callable $callable, $accumulator, Foldable $foldable) {
return reduce($callable, $accumulator, reduce(function ($accumulator, $value) {
return concatM(Listt::of([$value]), $accumulator);
}, Listt::of([]), $foldable));
}), func_get_args());
}
private function randomize()
{
return Listt::of(array_keys(array_fill(0, rand(20, 100), null)));
}
public function test_it_traverse_nothing()
{
$list = Listt::of([1, 2, 3, 4]);
$result = f\traverse('example\\value_is', $list);
$this->assertEquals(m\nothing(), $result);
}