sirocco https://blog.hatena.ne.jp/sirocco/ sirocco の書いてもすぐに忘れるメモ https://sirocco.hatenadiary.org/ Haskell lookup 関数は Maybe モナドを返す Prelude> :t lookup lookup :: (Eq a) => a -> [(a, b)] -> Maybe b Prelude> let taro = ("taro",[("sex","male"),("address","chiba")]) Prelude> let jiro = ("jiro",[("sex","male"),("address","tokyo")]) Prelude> let person = [taro,jiro] Prelude> person [("taro",[("sex","male"),("add… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fsirocco.hatenadiary.org%2Fentry%2F20090417%2F1239915676" title="lookup 関数は Maybe モナドを返す - sirocco の書いてもすぐに忘れるメモ" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2009-04-17 06:01:16 rich https://sirocco.hatenadiary.org/entry/20090417/1239915676 1.0 100%