Implementing Higher-Kinded Types in Dotty
The document discusses four approaches to implementing higher-kinded types in the Dotty compiler: the simple encoding, projection encoding, refinement encoding, and direct representation. It describes each approach and its limitations. The simple encoding provides a modest way to support basic higher-kinded concepts but has difficulty explaining legality. The projection and refinement encodings ha
Tail calls, @tailrec and trampolines
Recursion is an essential part of functional programming. But if each call allocates a stack frame, then too much recursion will overflow the stack. Most functional programming languages solve this problem by eliminating stack frames through a process called tail-call optimisation. Unfortunately for Scala programmers, the JVM doesn’t perform this optimisation. Here’s a picture of a Scala program a
Functional Dependencies in Scala - Miles Sabin
Functional dependencies are a near-standard extension to Haskell (present in GHC and elsewhere) which allow constraints on the type parameters of type classes to be expressed and then enforced by the compiler. They allow the programmer to state that some of the type parameters of a multi-parameter type class are completely determined by the others. One particularly common application of this is al
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ã“ã®ã‚¨ãƒ³ãƒˆãƒªã¯Scalaアドベントカレンダーã®3日目ã§ã™ã€‚昨日㯠Kuchitama ã•ã‚“ã®ScalaãŒã¤ãªã„ã§ãã‚ŒãŸç¸-NetflixMeetup Kyoto 開催後記- ã§ã—ãŸã€‚ å‰ãŠã ã“ã®è¨˜äº‹ã¯ã€ã‚¿ã‚¤ãƒˆãƒ«é€šã‚ŠFreeモナドã¨Coyonedaを扱ã†ã‚‚ã®ã®ã€ã‚ã¾ã‚Šãれらã®ç›´æŽ¥çš„ãªè©±ã‚„モナモナã—ãŸè©±ã§ã¯ãªãã€ãã“ã«è‡³ã‚‹ã¾ã§ã®å®Ÿè£…ã®ã‚ã‚Œã“れを『Scalaã®ãƒ—ãƒã‚°ãƒ©ãƒŸãƒ³ã‚°ã¨ã—ã¦ã€æ‰‹æŽ¢ã‚Šã§è¿½ã£ã¦ã¿ã‚ˆã†ã€ã¨ã„ã†ã‚‚ã®ã§ã™ã€‚ ãã®éŽç¨‹ã§ã€ç‰¹ã«åž‹å¼•æ•°(型変数)や高階型やã€ãれらãŒç¶™æ‰¿æ™‚ã«ã©ã†æ‰±ãˆã‚‹ã‹ã¨ã„ã†ã‚ãŸã‚Šã®Scalaã®åŸºæœ¬ã«ãŸã£ã·ã‚Šè§¦ã‚Œã¾ã™ã€‚ ãªã®ã§ã€Freeモナドã«èˆˆå‘³ãŒãªã„æ–¹ã§ã‚‚ 型引数㧠A ã¨ã‹ F[_] ã¨ã‹å‡ºã¦ãã‚‹ã¨ã€ã¾ã ã¡ã‚‡ã£ã¨ã“ã‚ã„ Scalaã§ã„ã–プãƒã‚°ãƒ©ãƒŸãƒ³ã‚°ã™ã‚‹ã¨åž‹ãŒåˆã‚ãšã¤ã¾ã¥ã事ãŒå¤šã„ ã¨ã„ã†æ–¹ã«ã‚‚ã€å½¹ã«ç«‹ã¤éƒ¨åˆ†ãŒã‚ã‚‹ã¨æ€ã†ã®ã§å‚考ã«ãœã²èªã‚“ã§ã¿ã¦ã‚‚らã„ãŸã„ã§ã™ã€‚ ã‚‚ã¡
Functional Programming in Scala ã®æ„Ÿæƒ³ - xuwei-k's blog
http://www.manning.com/bjarnason https://github.com/pchiusano/fpinscala 一年ã¡ã‚‡ã£ã¨å‰ã«blog書ãã¾ã—ãŸãŒ Scalaz ã®ä½œè€…ã®äººé”ãŒæ›¸ã„㟠"Functional Programming in Scala" ã¨ã„ã†æœ¬ãŒã§ã‚‹ã‚‰ã—ã„ 14ç« ã®ãžã„ã¦ã»ã¼å®Œæˆã—ãŸã®ã§ã€æ„Ÿæƒ³æ›¸ãã¾ã™ã€‚MEAP v9ã®æ™‚点ã§ã™ã€‚ã¡ã‚‡ã£ã¨é•·ã„ã§ã™ã‚ˆã€‚ ã¾ãšã€å…¨ä½“を通ã—ã¦ã„ãˆã‚‹ã®ãŒã€Scalaã®æœ¬ã§ã¯ãªãã‚ãã¾ã§é–¢æ•°åž‹ãƒ—ãƒã‚°ãƒ©ãƒŸãƒ³ã‚°ã®æœ¬ã ã¨ã„ã†ã“ã¨ã§ã™ã€‚ãã‚Œã¯æœ¬æ–‡ã®æœ€åˆã®æ–¹ã«ã‚‚書ã„ã¦ã‚ã‚Šã¾ã™ã€‚ ã“ã®æœ¬ã ã‘èªã‚“ã§ã‚‚ã€Scala自体ã«ã¯ã‚ã¾ã‚Šè©³ã—ããªã‚Šã¾ã›ã‚“。Scala自体ã«ã¤ã„ã¦ã¯ã€å¿…è¦æœ€ä½Žé™ã®æ–‡æ³•ã ã‘ã‚’éšæ™‚説明ã—ã¦ã¾ã™ã€‚ 逆ã«ã€(英語ãŒèªã‚ã‚‹ãªã‚‰)Scalaã®çŸ¥è˜ãŒã»ã¼ã‚¼ãƒã ã¨ã—ã¦ã‚‚ã€å¤§ä½“èªã‚ã‚‹ã®ã§ã¯ãªã„ã‹ã¨æ€ã„ã¾ã™ã€‚ ã¾ãŸã€Scalazã®æœ¬ã§
Monad Transformers in Scala
A programmer's blog - will deal with everything that relates to a programmer. Occasionally, it will contain some humour, some politics and some sport news. Monads don't compose .. and hence Monad Transformers. A monad transformer maps monads to monads. It lets you transform a monad with additional computational effects. Stated simply, if you have a monadic computation in place you can enrich it in
Scalaã«ãŠã‘ã‚‹Javaã®ã‚¤ãƒ³ã‚¿ãƒ¼ãƒ•ã‚§ãƒ¼ã‚¹ã£ã¦ï¼Ÿ
t_yano @t_yano Scalaã«ã¤ã„ã¦ã¯traitã¨ã‹æ§‹é€ åž‹ã«ã¤ã„ã¦ã„ã‚ã„ã‚èžã„ã¦ã¿ãŸã„ã“ã¨ãŒã‚ã‚‹ã‚“ã ã‘ã©ã¨ã¦ã‚‚140æ–‡å—ã§ã¯è¡¨ã›ãªã„ãªâ€¦ã€‚ã¾ã‚ã€ã‚¹ã‚¿ã‚¤ãƒ«ã¨ã„ã†ã‹å®šçŸ³ã¨ã‹ãŒã©ã†ãªã£ã¦ã‚‹ã®ã‹çŸ¥ã‚ŠãŸã„ç³»ã®è©±ã ã‘ã©ã€‚ 2011-10-24 01:31:09 t_yano @t_yano ãªã‚“ã‹å®Ÿè£…継承ã™ã‚‹ã‚±ãƒ¼ã‚¹ã°ã‹ã‚Šã‚’見ã‹ã‘ã‚‹ã®ãŸã‘ã©ã€åž‹ã‚’定義ã™ã‚‹ãŸã‚ã«traitを使ã†ã¨ã‹ã€ã™ã¹ã¦ã®ã‚¯ãƒ©ã‚¹ã¯ãªã‚“らã‹ã®traitã‚’åž‹ã¨ã—ã¦æŒã¤ã¹ãã æ´¾ã¨ã‹ã€ã‚ã‚‹ã„ã¯é€†ã«ã€ã™ã¹ã¦ã®å¼•æ•°ã¯ç†ç”±ãŒãªã„é™ã‚Šæ§‹é€ 的部分型ã«ã™ã¹ãæ´¾ã¨ã‹ã€ãã†ã„ã†è©±ã¯ãªã„ã‚“ã ã‚ã†ã‹çš„ãªç–‘å•ã€‚ 2011-10-24 01:34:22 t_yano @t_yano ã‚ã‚‹ã„ã¯ã‚るクラスをå—ã‘å–ã‚‹ã¨å®šç¾©ã•ã‚Œã¦ã„る関数ã«ã€ãã®åž‹ã§ã¯ãªã„ã‘ã©äº‹å®Ÿä¸Šãã®æ–¹ã¨ã—ã¦æŒ¯ã‚‹èˆžãˆã‚‹åˆ¥ã®åž‹ã®ã‚ªãƒ–ジェクトをã€ãªã‚“らã‹ã®æ–¹æ³•ã§æ¸¡ã™ã“ã¨ãŒå¯èƒ½ãªã®ã§ã€é–¢æ•°ã‚¤ãƒ³ã‚¿ãƒ•ã‚§ãƒ¼
レãƒãƒ¬ãƒƒã‚¸ãƒ¡ãƒ¢: Scalaスケーラブルプãƒã‚°ãƒ©ãƒŸãƒ³ã‚° - 西尾泰和ã®ã¯ã¦ãªãƒ€ã‚¤ã‚¢ãƒªãƒ¼
言語も伽è—ã¨ãƒã‚¶ãƒ¼ãƒ«ã®ã‚ˆã†ã«æˆé•·ã™ã‚‹--Steele "Growing a language" 1999 トレイト=インターフェイスã«ä¼¼ã¦ã„ã‚‹ãŒãƒ¡ã‚½ãƒƒãƒ‰å®Ÿè£…やフィールドをæŒã¤ã€ãƒŸãƒƒã‚¯ã‚¹ã‚¤ãƒ³åˆæˆå‡ºæ¥ã‚‹ Javaã®Stringã«toIntãŒãªã„ã“ã¨ã«æ°—ã¥ã„ãŸã¨ãã«ã€æš—é»™ã®åž‹å¤‰æ›ã‚’å‚ç…§ã—ã¦RichStringã«å¤‰æ›ã—ã€ãã®toIntを呼㶠アラン・ケイ「ç§ã¯åž‹ã«å対ã—ã¦ã„ã‚‹ã‚ã‘ã§ã¯ãªã„。『完全ãªè‹¦ç—›ã€ã«ã¯ãªã‚‰ãªã„よã†ãªåž‹ã‚·ã‚¹ãƒ†ãƒ を見ãŸã“ã¨ãŒãªã„ã®ã§å‹•çš„ãªç‰‡ä»˜ã‘を支æŒã—ã¦ã„ã‚‹ã®ã§ã‚ã‚‹ã€2003 Dr. Alan Kay on the Meaning of "Object-Oriented Programming" ダイクストラ「テストãŒè¨¼æ˜Žã§ãã‚‹ã®ã¯ã‚¨ãƒ©ãƒ¼ã®å˜åœ¨ã§ã‚ã£ã¦ã€ã‚¨ãƒ©ãƒ¼ã®ä¸åœ¨ã§ã¯ãªã„〠1970 http://www.cs.utexas.edu/users/EWD/ewd02xx/EWD2
Type safe mongodb with Scala #montotokyo
Type safe mongodb with Scala #montotokyo 1. Type-safe MongoDB in Scala - é™çš„型付ã‘言語ã¨MongoDBã®ä»˜ãåˆã„æ–¹ -Fungoing LLC / Satoshi MiyauchiTwitter : @bibrost 2. Profile 宮内 è– / Satoshi Miyauchi @bibrost フゔンゴー゗ングåˆåŒä¼šç¤¾ä»£è¡¨ å…¼ æ ªå¼ä¼šç¤¾ç›£æŸ»ã¨åˆ†æž システム開発担当 Webデザ゗ンã€æ˜ åƒç·¨é›†ã€Webサービスã®é–‹ç™ºãªã©ãƒ»ãƒ»ãƒ»ã„ã‚ã„゠引ãã“もりフリーランス生活 Scala＋Lift＋MongoDBã®çµ„ã¿åˆã‚ã›ã‚’昨年11月より利用ä¸ã€‚ 自社サービス１ã¤ã€ã‚¯ãƒ©ã‚—ゕントワーク１ã¤ã§Scala+MongoDBを利用。 Page : 1 3. Case Example å‹é–“和代æ°ã®æä¾›ã™ã‚‹æœ‰æ–™ã‚³ãƒ³ãƒ†ãƒ³ãƒ„会員å‘ã‘コミュニテ
書評:プãƒã‚°ãƒ©ãƒŸãƒ³ã‚°Scala - The Python Paradox is now the Scala Paradox - ( ꒪⌓꒪) ゆるよã‚日記
ã‚ªãƒ©ã‚¤ãƒªãƒ¼ã‚¸ãƒ£ãƒ‘ãƒ³æ§˜ã‚ˆã‚ŠçŒ®æœ¬é ‚ãã¾ã—ãŸã€‚èªäº†ã—ãŸã®ã§ã€æ„Ÿæƒ³ãªã©æ›¸ã„ã¦ã¿ãŸã„ã¨æ€ã„ã¾ã™ã€‚ プãƒã‚°ãƒ©ãƒŸãƒ³ã‚°Scalaposted with amazlet at 11.02.19Dean Wampler Alex Payne オライリージャパン 売り上ã’ランã‚ング: 69951 Amazon.co.jp ã§è©³ç´°ã‚’見る The Python Paradox is now the Scala Paradox ãªã‚“ã§ã™ãŒã€æœ¬ã®ç´¹ä»‹ã«å…¥ã‚‹å‰ã«ã€ã¨ã‚る記事ã®ç´¹ä»‹ã‚’ã—ãŸã„ã¨æ€ã„ã¾ã™ã€‚ The Python Paradox is now the Scala Paradox — Martin Kleppmann‘s blog In his 2004 short essay The Python Paradox, PG argues (perhaps controversially) that a compan
Java使ã„ã‚’Scalaã«å¼•ã込むサンプル集 | mwSoft
å‰æ›¸ã Scalaã¨ã„ã†è¨€èªžã‚’ã”å˜çŸ¥ã§ã™ã‹ï¼Ÿ Javaã¨åŒã˜ãコンパイルã•ã‚Œã‚‹ã¨classファイルã«ãªã‚Šã€å®Ÿè¡Œæ™‚ã¯JVM上ã§å‹•ä½œã™ã‚‹ã€ã‚ªãƒ–ジェクト指å‘＋関数型ã®ãƒ—ãƒã‚°ãƒ©ãƒŸãƒ³ã‚°è¨€èªžã§ã™ã€‚ Scalaを開発ã—ãŸã®ã¯Javaã®genericsã®è¨è¨ˆã‚’手ãŒã‘ãŸã‚Šã€javacã®é–‹ç™ºã‚’ã—ã¦ã„ãŸçµŒæ´ã‚‚æŒã¤Martin Oderskyæ°ã€‚ Scalaã¯å¾Œç™ºã®è¨€èªžã¨ã„ã†ã“ã¨ã‚‚ã‚ã£ã¦ã€Javaを書ã„ã¦ã„る時ã«æ„Ÿã˜ã‚‹å†—é•·ã•ã«å¯¾ã™ã‚‹æ§˜ã€…ãªè§£ãŒç”¨æ„ã•ã‚Œã¦ã„ã¾ã™ã€‚ 本記事ã§ã¯ã€Scalaã¨Javaã®ã‚³ãƒ¼ãƒ‰ã‚’比較ã—ãªãŒã‚‰ã€JavaユーザãŒScalaã«ç§»ã£ãŸéš›ã«å¾—られるメリットをæ示ã—ã¦ã„ãã¾ã™ã€‚ å°šã€åºç›¤ã®ã‚µãƒ³ãƒ—ルコードã¯Javaユーザã«ä¼ã‚ã‚Šã‚„ã™ã„よã†ã«ã€returnを明記ã—ãŸã‚Šã€ãƒ¡ã‚½ãƒƒãƒ‰ã¯å¿…ãš{ }ã§å›²ã‚€ãªã©ã€æ¥µåŠ›Javaã£ã½ã„記述をã—ã¦ã„ã¾ã™ã€‚ ã ã„ãŸã„Javaã¨åŒã˜ã‚ˆã†ãªæ›¸ãæ–¹ãŒã§ãã¾ã™ Scalaã¯Javaã®
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