etorreborre

/**
 * this is an experiment to create unboxed union types with a phantom type and a context bound.
 * All the good ideas come from @milessabin post, comments and links: http://www.chuusai.com/2011/06/09/scala-union-types-curry-howard/#comment-22
 */

/** trait for anything that can be A or B */
trait Or[A, B] {
  // a phantom type, there will be no instance of this type that we'll use
  type l[T]
  // an alias for l[t]

gakuzzzz

scala> def add(i: Int)(words: String) = words.map({x: Char => x + i - 'a'} andThen Stream.continually(Range.inclusive('a', 'z')).flatten andThen {_.toChar})
add: (i: Int)(words: String)String

scala> add(2)("abcdz")
res16: String = cdefb

lyricallogical

imoprt Iteratee._

lazy val takeOdds = {
  val aux = for {
   one <- headOption[Byte[Array]] // ダサい
    _ <- headOption[Byte[Array]] // ダサい
  } yield one

  for {
    odds <- aux

lyricallogical

lazy val fab: PartialFunction[Base, Int] = {
  case A(base) => 1 + fabc(base) // PartialFunction#apply の呼び出し。危ない！
  case B(left, right) => 1 + fabcd(left) + fabcd(right) // 同様
}

// 全域関数だと scala コンパイラにはわからない！
lazy val fabcd: PartialFunction[Base, Int] = fab orElse {
  case C => 1
  case D => 2
}

tk0miya

Usage
======

.. wiki-table::
   :header-rows: 1
   :widths: 2 3 5

   |id|header1|header2|
   |1|hello|world|
   |2|foo|:strong:`bar`|

xuwei-k

原文: http://apocalisp.wordpress.com/2010/07/02/higher-rank-polymorphism-in-scala/ 訳者は英語得意ではなく、訳が怪しいところがあるとおもうので、間違いやつっこみがあれば、ここのコメント欄に記入なりなんなり指摘お待ちしてます。

Scalaでの高ランクポリモーフィズム (Higher-Rank Polymorphism in Scala)

Tim Carstens のポスト Haskell features he’d like to see in other languages をよんで、そのなかの一つにrank-2 typesというものがありました。 Tim は、これ(rank-2 type)を使ったキラーアプリケーションとして、型システムを利用して、リソースへのアクセスの安全性を確保するといいます。

swannodette

;; based on core.logic 0.8-alpha2 or core.logic master branch

(ns sudoku
  (:refer-clojure :exclude [==])
  (:use clojure.core.logic))

(defn get-square [rows x y]
  (for [x (range x (+ x 3))
        y (range y (+ y 3))]
    (get-in rows [x y])))

matope

Cassandra - A Decentralized Structured Storage System

---

原文: Cassandra - A Decentralized Structured Storage System

This article is translated by @ono_matope. Please contact me if any problem.

---

tototoshi

// import scala.collection.JavaConversions._

scala> val git = new Git(new FileRepositoryBuilder().findGitDir(new java.io.File("/path/to/repos")).readEnvironment().build())
git: org.eclipse.jgit.api.Git = org.eclipse.jgit.api.Git@18ed36fb

scala> git.log.addPath("foo").call.head
res49: org.eclipse.jgit.revwalk.RevCommit = commit c4554d9f46de49e449242a2aa75d39874dc99498 1342332998 ----sp

scala> git.log.addPath("foo").call.headOption
res50: Option[org.eclipse.jgit.revwalk.RevCommit] = Some(commit d3107ef998b25d70f86f1a5d530c31c02507d59e 1342012813 ----sp)

halcat0x15a

(use 'clojure.core.logic)

(def _1 [()])

(def _2 [() ()])

(def _3 [() () ()])

(def _4 [() () () ()])