README

Result and Option type for your functions returned values.

Result<T,E> is the type used for returning and propagating errors. It is either an Ok(T), representing success and containing a value, er an Error(E), representing error and containing an error value.

Type Option represents an optional value: every Option is either Some and contains a value, or None, and does not. Option types have a number of uses:

Initial values
Return values for functions that are not defined over their entire input range (partial functions)
Return value for otherwise reporting simple errors, where None is returned on error
Optional class properties
Optional function arguments
Nullable values

Option is the type used for a value either containing a T or nothing.

Result Usage

Full API documentation

Declaring and writing a function returning a Result

/**
 * @return Result<string,string>
 */
function readFile(string $path): Result
{
    return match ($content = file_get_contents($path)) {
        false => Result::error("file at $path could not be read"),
        default => Result::ok($content),
    };
}

Using a Result

Checking if the result is an error or not:

$content = readFile("/path/to/file");

if ($content->isError()) die("{$content->unwrapError()}" . PHP_EOL);

echo $content->unwrap();

Working on the result:

/**
 * @param Result<string,string>
 * @return Result<int,string>
 */
function length(Result $o): Result
{
    return $o->map("strlen");
}

Option Usage

Declaring and writing a function returning an Option

/**
 * @return Option<string>
 */
function firstChar(string $s): Option
{
    return match (true) {
        $s === "" => Option::none(),
        default   => Option::value($s[0]),
    };
}

Using an Option value