| ;fac | |
| (defn fac [n] | |
| (if (zero? n) 1 | |
| (* n (fac (dec n))))) | |
| (defn fac-t [n acc] ; n 1 | |
| (if (zero? n) acc | |
| (recur (dec n) (* acc n)))) | |
| (defn fac-c [n f] ; n identity |
Stream是一种能容纳无穷对象的容器，我在研究了Js的实现后，尝试用Ruby实现一下。另外加上阶乘数列和 费波纳茨数列的实现。
Stream.js的介绍： http://www.aqee.net/stream-javascript-lib/
Stream的详情请参考： http://www.aqee.net/docs/stream/
class Stream
def initialize(head = nil, tail = nil)
@head = head
@tailFunc = tail
end
在LISP之根源里面看到作者提到Y组合子，于是去了解了一下，但是看其他人的解释都很难完全弄懂。
最后通过 王垠的wiki 发现 Franco 教授的推演过程讲得最简单易懂，在看懂了之后我再用CoffeeScript推演了一次，加深理解。
LISP之根源 http://daiyuwen.freeshell.org/gb/rol/roots_of_lisp.html#foot108
王垠的wiki http://minus273.eu/mirrors/2001315450/wiki/SchemeYcombinator.html
Franco 教授的推演过程 http://www.ece.uc.edu/~franco/C511/html/Scheme/ycomb.html
可以将代码贴在这里上面验证结果 http://coffeescript.org/
public static float dp2Px(float dp, Context context){
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
return dp * (metrics.densityDpi / 160f);
}
public static float px2Dp(float px, Context context) {
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
return px / (metrics.densityDpi / 160f);
}| set nocompatible | |
| source $VIMRUNTIME/vimrc_example.vim | |
| source $VIMRUNTIME/mswin.vim | |
| behave mswin | |
| set diffexpr=MyDiff() | |
| function MyDiff() | |
| let opt = '-a --binary ' | |
| if &diffopt =~ 'icase' | let opt = opt . '-i ' | endif | |
| if &diffopt =~ 'iwhite' | let opt = opt . '-b ' | endif |
| // http://www.cnblogs.com/youxilua/archive/2013/05/20/3087935.html | |
| // https://github.com/evant/gradle-retrolambda | |
| // http://tools.android.com/tech-docs/new-build-system/user-guide | |
| buildscript { | |
| repositories { | |
| mavenCentral() | |
| } | |
| dependencies { |
| buildscript { | |
| repositories { | |
| mavenCentral() | |
| } | |
| dependencies { | |
| classpath 'com.android.tools.build:gradle:0.4' | |
| } | |
| } | |
| apply plugin: 'android' |
| [user] | |
| email = heganjie@gmail.com | |
| name = heganjie | |
| [gui] | |
| encoding = utf-8 | |
| [branch] | |
| autosetupmerge = always | |
| [alias] | |
| aa = add -A | |
| st = status |
Java/Android case insensitive contains and indexOf
O(n), no Object creating, no GC, should be faster than Pattern.CASE_INSENSITIVE?
public static boolean equalsIgnoreCaseInString(String longer, int ai, String shorter, int bi) {
int chkLen = shorter.length() - bi;
if (longer.length() - ai < chkLen) return false;
for (int c = 0; c < chkLen; ai++, bi++, c++) {
char ac = longer.charAt(ai);
char bc = shorter.charAt(bi);
| :: http://pngquant.org/ | |
| @echo off | |
| set path=%~d0%~p0 | |
| :start | |
| "%path%pngquant.exe" --force --ext .png --verbose --ordered --speed=1 --quality=50-90 %1 |