function retrieveRelated($productName)
{
return S::of(function (Cacher $cache) use($productName) {
// do some database work
$products = ['iPhone 5', 'iPhone 6s'];
return [$products, $cache->put($productName, $products)];
});
}
/**
* ioState :: IO a -> State IO a
*
* @param M\IO $io
*
* @return M\State
*/
function ioState(M\IO $io)
{
return M\State::of(function ($state) use($io) {
list($key, $data) = $state;
$value = $io->run();
$data[$key] = $value;
$newState = [$key, $data];
return [$value, $newState];
});
}
/**
* runState :: State s a -> s -> (a, s)
*
* Unwrap a state monad computation as a function.
*
* @param M\State $state
* @param mixed $initialState
*
* @return mixed
*/
function runState(M\State $state, $initialState)
{
return $state->runState($initialState);
}
