大魔头 notyy

a consultant work in @ThoughtWorksInc china office. functional programming fans. like scala,haskell,elm.

notyy / gist:1234930

Created September 22, 2011 14:35

can match any parameter

	def tryMatch: PartialFunction[Any, Unit] = {
	case s:String => println("its a string:" + s)
	case (s1:String,s2:String) => println("two strings:" + s1 + " and "+ s2)
	case i:Int => println("its a int:" + i)
	}

notyy / gist:1235065

Created September 22, 2011 15:28

onsubmit def

	def onSubmit (func: (String) ⇒ Any): (NodeSeq) ⇒ NodeSeq
	execute the String function when the form is submitted. This method returns a function that can be applied to form fields (input, button, textarea, select) and the function is executed when the form containing the field is submitted.

	object ChatIn {

	/**
	* The render method in this case returns a function
	* that transforms NodeSeq => NodeSeq. In this case,
	* the function transforms a form input element by attaching
	* behavior to the input. The behavior is to send a message

notyy / gist:1241798

Created September 26, 2011 07:42

width no use?

	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml">
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
	<title>无标题文档</title>
	</head>

	<body>
	<p> </p>
	<input id="shellcommand_in" width="800"/>

notyy / gist:1292865

Created October 17, 2011 15:29

pattern matching haskell vs scala

	addList :: (Num a) => [(a,a)] -> [a]
	addList xs = [x + y \| (x,y) <- xs]

	def addList(xs:List[(Int,Int)]): List[Int] = for((x,y) <- xs) yield(x+y)

notyy / gist:1312942

Created October 25, 2011 14:34

how to implement this in scala?

	quicksort' :: (Ord a) => [a] -> [a]
	quicksort' [] = []
	quicksort' (x:xs) = smaller ++ [x] ++ bigger
	where smaller = quicksort' $ filter (<=x) xs
	bigger = quicksort' $ filter (>x) xs

notyy / gist:1313294

Created October 25, 2011 16:12

quicksort in lisp

	user=> (defn qs [l]
	(if (< (count l) 2) l
	(let [left (filter #(< % (first l)) (rest l))
	right (filter #(>= % (first l)) (rest l))]
	(concat left (list (first l)) right))))

notyy / gist:1321966

Created October 28, 2011 09:35

change to func

	def assertArray(b1: Array[Byte], b2: Array[Byte]) {
	if (b1 == null && b2 == null) return;
	else if (b1 != null && b2 != null) {
	if (b1.length != b2.length) throw new AssertionError("b1.length != b2.length")
	else {
	for (i <- b1.indices) {
	if (b1(i) != b2(i)) throw new AssertionError("b1(%d) != b2(%d)".format(i, i))
	}
	}
	} else {

notyy / gist:1321990

Created October 28, 2011 09:51

sand...

	def assertArray[T](b1: Option[Array[T]], b2: Option[Array[T]]):Boolean = (b1,b2) match {
	case (None,None) => true
	case (Some(arr1),Some(arr2)) if(arr1.toList == arr2.toList) => true
	case (_,_) => false
	}

notyy / gist:1322045

Created October 28, 2011 10:35

flatmap

	def toInt(in: String): Option[Int] =
	try {
	Some(Integer.parseInt(in.trim))
	} catch {
	case e: NumberFormatException => None
	}

	def sum(in: Seq[String]) = {
	val ints = in.flatMap(s => toInt(s))
	ints.foldLeft(0)((a, b) => a + b)

notyy / gist:1322186

Created October 28, 2011 12:48

high order function

	def mymap[A,B](xs:List[A],f: A => B): List[B] = {
	xs.map(f)
	}

	scala> mymap(List(1,2,3),((_:Int)*2))
	res2: List[Int] = List(2, 4, 6)

	scala> mymap(List(1,2,3),((_:Int).toString))
	res3: List[java.lang.String] = List(1, 2, 3)