<commit_before><?hh // strict
namespace FH;

final class IO<T> {
    public function __construct(private (function(): T) $action) { }

    public function unsafePerform(): T {
        return call_user_func($this->action);
    }

    public function map<TM>((function(T): TM) $f): IO<TM> {
        return new IO(function() use($f) {
            $x = $this->unsafePerform();
            return $f($x);<commit_msg>Make IO covariant<commit_after><?hh // strict
namespace FH;

final class IO<+T> {
    public function __construct(private (function(): T) $action) { }

    public function unsafePerform(): T {
        return call_user_func($this->action);
    }

    public function map<TM>((function(T): TM) $f): IO<TM> {
        return new IO(function() use($f) {
            $x = $this->unsafePerform();
            return $f($x);
{'fraction_non_alphanumeric': 0.1608222490931076, 'fraction_numerical': 0.0, 'mean_word_length': 2.924170616113744, 'pattern_counts': {'":': 0, '<': 11, '<?xml version=': 0, '>': 13, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '6231983', 'n_tokens_mistral': 264, 'n_tokens_neox': 253, 'n_words': 67}