README

A set of tools to enable a more functional style of programming in PHP, inspired by OCaml.

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<?php

// lots of list utility functions
list($even, $odd) = Lst::partition(fn (int $num) => $num % 2 === 0, [1, 2, 3, 4, 5, 6]);
// $even is [2, 4, 6]
// $odd is [1, 3, 5]

// pipe a bunch of operations
Collection::from(Lst::init(fn (int $index) => $index * $index, 100))
 ->filter(fn (int $num) => $num % 2 === 0)
 ->filter(fn (int $num) => $num > 50)
 ->map(fn (int $num, int $index) => $num * $index)
 ->foldl(fn (int $acc, int $val) => $acc + $val, 0);

// better error handling with Result
function safeDivision(int $a, int $b): Result
{
 if ($b === 0) {
 return Result::error("cant divide by 0");
 }

 return Result::ok($a / $b);
}

$res = safeDivision(10, 2);

if ($res->hasError()) {
 print($res->value());
 exit(1);
}

// use bind for Result or Option to only continue as long as there is a value
// lets assume we have a function fetch(string $url): Result that just returns
// the response as a string wrapped into Result
$title = fetch("https://atomicptr.dev/api/blog/post/1337")
 ->bind(fn (string $response) => Result::capture(fn () => json_decode($resp, true, flags: JSON_THROW_ON_ERROR)))
 ->bind(function (array $data) {
 assert(BlogPostSchema::isValid($data)); // A ficticious json schema validator
 return BlogPostResource::createFrom($data); // This converts the json data into a structure
 })->bind(fn (BlogPost $post) => $post->title());

if ($title->hasError()) {
 // something went wrong along the chain, so just panic
 $title->panic();
 exit(1);
}

// express "nothing" without using null
function findOneById(int $id): Option
{
 $rows = DB::find("table_name", ["id" => $id]);

 if (empty($rows)) {
 return Option::none();
 }

 return Option::some($rows[0]);
}

$row = findOneById(1337);

if ($row->isNone()) {
 print("Can not find object 1337");
 exit(1);
}

// ...

// maps
$incrementer = fn (Option $value) => $value->isSome() ? Option::some($value->value() + 1 : 1;
$map = Map::empty()
 ->update("a", $incrementer)
 ->update("a", $incrementer)
 ->update("b", $incrementer)
 ->set("c", 5);

$map->get("a"); // 3
$map->get("b"); // 1

// group products by type
$productsByType = Lst::groupBy(fn (Product $product) => $product->getType()->toString(), Product::all());
$productsByType->get("electronics") // [Product, Product]

// memoize functions
$f = Memo::make(fn (int $a, int $b) => doSomethingHeavy($a, $b));
$res = $f(1337, 8080); // this will call "doSomethingHeavy" which might take a while
// ...
$res = $f(1337, 8080); // now we call it again but it will now instantly return the result because we already called it with 1 and 2

Install

The package is available on packagist

Install via:

$ composer req atomicptr/functional

Docs

Atomicptr\Functional

• Lst
• Collection
• Option
• Result
• Map

Atomicptr\Functional\Traits

• EnumCollectionTrait

Atomicptr\Functional\Exceptions

• ResultError
• ImmutableException

License

MIT