{"blog_url":"https://www.shigemk2.com/","image_url":null,"url":"https://www.shigemk2.com/entry/covariant_type_X","author_url":"https://blog.hatena.ne.jp/shigemk2/","title":"\u72ec\u7fd2Scalaz\u306b\u304a\u3051\u308b error: covariant type X occurs in invariant position in type [+X]ReaderTOption[C,X] of type l","version":"1.0","categories":["Scala"],"type":"rich","width":"100%","description":"\u72ec\u7fd2Scalaz 10\u65e5\u76ee \u30e2\u30ca\u30c9\u5909\u63db\u5b50 \u306b\u3066\u3001\u30a8\u30e9\u30fc\u306b\u306a\u308b\u3068\u3053\u308d\u3092\u898b\u3064\u3051\u307e\u3057\u305f\u3002 scalaz 7.1.x scala 2.11.7 \u305d\u306e\u307e\u307e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u3092\u306a\u305e\u308b\u3068\u3001\u30bf\u30a4\u30c8\u30eb\u306e\u3088\u3046\u306a\u30a8\u30e9\u30fc\u306b\u306a\u308b\u3002 scala> :paste // Entering paste mode (ctrl-D to finish) type StateTReaderTOption[C, S, A] = StateT[({type l[+X] = ReaderTOption[C, X]})#l, S, A] object StateTReaderTOption extends StateTInstances wit\u2026","height":"190","published":"2015-08-29 01:32:33","author_name":"shigemk2","provider_name":"Hatena Blog","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fwww.shigemk2.com%2Fentry%2Fcovariant_type_X\" title=\"\u72ec\u7fd2Scalaz\u306b\u304a\u3051\u308b error: covariant type X occurs in invariant position in type [+X]ReaderTOption[C,X] of type l - by shigemk2\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","provider_url":"https://hatena.blog","blog_title":"by shigemk2"}