public function provideFunctorTestData()
{
return ['IO' => ['$f' => function ($x) {
return $x + 1;
}, '$g' => function ($x) {
return $x + 5;
}, '$x' => IO::of(function () {
return 1;
})]];
}
/**
* tryCatch :: Exception e => IO a -> (e -> IO a) -> IO a
*
* @param M\IO $io
* @param callable $catchFunction
*
* @return M\IO
*/
function tryCatch(M\IO $io = null, callable $catchFunction = null)
{
return call_user_func_array(f\curryN(2, function (M\IO $io, callable $catchFunction) {
return M\IO::of(function () use($io, $catchFunction) {
try {
return $io->run();
} catch (\Exception $e) {
return call_user_func($catchFunction, $e);
}
});
}), func_get_args());
}
/**
* doo :: State IO m => [m a] -> m a
*
* Haskell like "do notation" simple implementation.
* Since "do" is reserved keyword in PHP then I use "doo".
*
* @param array|M\IO[] $monads
*
* @return M\IO
*/
function doo(array $monads)
{
return M\IO::of(function () use($monads) {
$result = null;
$data = [];
// TODO do it by foldWithKeys
foreach ($monads as $key => $monad) {
// TODO do it better - maybe?
if ($monad instanceof M\IO) {
$monad = ioState($monad);
}
$state = [$key, $data];
list($result, list(, $data)) = M\State\runState($monad, $state);
}
return $result;
});
}
/**
* getEnv :: String -> IO String
*
* @param string $name
*
* @throws IOError
*
* @return M\IO
*/
function getEnv($name)
{
return M\IO::of(function () use($name) {
$value = \getenv($name);
if (false === $value) {
throw userError(sprintf('Environment variable "%s" does not exists.', $name));
}
return $value;
});
}
