add hash implementation

README.md

@@ -4,7 +4,7 @@
 [![codecov](https://codecov.io/gh/innmind/hash/branch/develop/graph/badge.svg)](https://codecov.io/gh/innmind/hash)
 [![Type Coverage](https://shepherd.dev/github/innmind/hash/coverage.svg)](https://shepherd.dev/github/innmind/hash)
 
-Description
+This component allows to incrementally compute the hash of a file (or any sequence of strings).
 
 ## Installation
 
@@ -14,4 +14,66 @@ composer require innmind/hash
 
 ## Usage
 
-Todo
+```php
+use Innmind\OperatingSystem\Factory;
+use Innmind\Url\Path;
+use Innmind\Hash\{
+    Hash,
+    Value,
+};
+use Innmind\Immutable\Set;
+
+$hashes = Factory::build()
+    ->filesystem()
+    ->mount(Path::of('some-folder/'))
+    ->all()
+    ->map(Hash::sha512->ofFile(...));
+$hashes; // Set<Value>
+```
+
+Since the computation doesn't rely on the filesystem it can be called on content that is not on the filesystem.
+
+Examples:
+
+```php
+use Innmind\OperatingSystem\Factory;
+use Innmind\Http\{
+    Message\Request\Request,
+    Message\Method,
+    ProtocolVersion,
+};
+use Innmind\Url\Url;
+use Innmind\Server\Control\Server\Command;
+use Innmind\Hash\{
+    Hash,
+    Value,
+};
+
+$os = Factory::build();
+$os
+    ->remote()
+    ->http()(new Request(
+        Url::of('https://github.com'),
+        Method::get,
+        ProtocolVersion::v20,
+    ))
+    ->map(static fn($success) => $success->response()->content())
+    ->map(Hash::sha512->ofContent(...))
+    ->match(
+        static fn($value) => $value, // Value
+        static fn() => null, // http call failed
+    );
+
+$output = $os
+    ->control()
+    ->processes()
+    ->execute(
+        Command::foreground('git')
+            ->withOption('version'),
+    )
+    ->output()
+    ->chunks()
+    ->map(static fn($chunk) => $chunk[0]); // to only keep the chunk data
+
+Hash::sha512->ofSequence($output); // Value
+```

composer.json

@@ -15,7 +15,9 @@
         "issues": "http://github.com/innmind/hash/issues"
     },
     "require": {
-        "php": "~8.1"
+        "php": "~8.1",
+        "innmind/immutable": "~4.5",
+        "innmind/filesystem": "^5.2"
     },
     "autoload": {
         "psr-4": {