{"type":"rich","blog_url":"https://hiratara.hatenadiary.jp/","categories":["\u6280\u8853","\u6570\u5b66"],"image_url":null,"html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fhiratara.hatenadiary.jp%2Fentry%2F20111009%2F1318166846\" title=\"Catamorphism \u306e\u4ed6\u306e\u4f8b - Pixel Pedals of Tomakomai\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","published":"2011-10-09 22:27:26","provider_name":"Hatena Blog","author_name":"hiratara","author_url":"https://blog.hatena.ne.jp/hiratara/","provider_url":"https://hatena.blog","height":"190","title":"Catamorphism \u306e\u4ed6\u306e\u4f8b","url":"https://hiratara.hatenadiary.jp/entry/20111009/1318166846","description":"Catamorphism\u3092\u4f7f\u3063\u3066\u4e8c\u5206\u6728\u3067\u306e\u7573\u307f\u8fbc\u307f\u3092\u5b9a\u7fa9\u3059\u308b\u3068\u6bd4\u3079\u308b\u3068\u95a2\u9023\u304c\u898b\u3048\u3066\u304f\u308b\u304b\u3082\uff1f \u30ea\u30b9\u30c8\u306e\u7573\u307f\u8fbc\u307f \u81ea\u5df1\u95a2\u624bF\u3068\u3057\u3066\u3001\u578bX\u30921+A*X\u3078\u79fb\u3059\u3082\u306e\u3092\u3068\u308b\u30021+A*ArrayRef A\u2192ArrayRef A \u306a\u308b\u4ee5\u4e0b\u306eF\u4ee3\u6570\u304c\u59cb\u5bfe\u8c61\u3068\u306a\u308b\u3002 sub array(;$$) { @_ == 0 ? [] # type 1 : [$_[0], @{$_[1]}]; # type A*ArrayRef A } Catamorphism \u3092\u7b97\u51fa\u3059\u308bfoldl::(1+A*X\u2192X)\u2192ArrayRef A\u2192X \u306f\u4ee5\u4e0b\u3002 sub foldl(&) { my $f = shift; my $result\u2026","version":"1.0","width":"100%","blog_title":"Pixel Pedals of Tomakomai"}