如何绑定到函数的右侧?例:
var square = Math.pow.bindRight(2);
console.log(square(3)); //desired output: 9
Run Code Online (Sandbox Code Playgroud) 在定义变量,函数等之后,您是否可以将您在REPL上所做的事情保存为文本.clj文件?
我得到了这个例外:
10-24 17:08:19.711: E/AndroidRuntime(1379): FATAL EXCEPTION: main
10-24 17:08:19.711: E/AndroidRuntime(1379): java.lang.RuntimeException: Unable to start activity ComponentInfo{br.com.campusfqm.cfqm/br.com.campusfqm.cfqm.DownloadManagerActivity}: java.lang.IllegalStateException: Unable to create directory: /mnt/sdcard/Download
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1736)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1752)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.app.ActivityThread.access$1500(ActivityThread.java:123)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:993)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.os.Handler.dispatchMessage(Handler.java:99)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.os.Looper.loop(Looper.java:126)
10-24 17:08:19.711: E/AndroidRuntime(1379): at android.app.ActivityThread.main(ActivityThread.java:3997)
10-24 17:08:19.711: E/AndroidRuntime(1379): at java.lang.reflect.Method.invokeNative(Native Method)
10-24 17:08:19.711: E/AndroidRuntime(1379): at java.lang.reflect.Method.invoke(Method.java:491)
10-24 17:08:19.711: E/AndroidRuntime(1379): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
10-24 17:08:19.711: E/AndroidRuntime(1379): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
10-24 17:08:19.711: …
Run Code Online (Sandbox Code Playgroud) 与仅通过 AJAX 提供信息相比,使用 TCP 编程的站点(即站点上的某人连接到服务器并通过 TCP 交换信息)如何扩展?假设交换的信息是相同的。
试图澄清一下:我特别询问规模:我读到,与仅静态提供信息相比,保持数千个 TCP 连接需要资源(哪个?)。我想知道这是否正确。
是否有一个函数来测试片段是否是有效的JavaScript而没有实际评估它?也就是说,相当于
function validate(code){
try { eval(code); }
catch(err) { return false; }
return true;
};
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没有副作用.
是否可以将函数作为完全独立的node.js进程运行?例如:
var parallel = require("parallel");
parallel(function(){
var app = require("express")();
app.on("/",function(req,res){ res.send("hi"); });
app.listen(80);
},function callback(err,stdout){
console.log("process terminated!")
});
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有可能吗?
没有更好的事情,我已经了解到如果你在vim上打开以下文字:
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...设置以下地图:
:noremap t ddGpgg
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...按住"t"键,你会看到一个很酷的正弦波.
另一方面,这个:
:noremap t ddGpMddGpgg
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用一种很酷的DNA旋转动画来颂扬你的眼睛.VIM映射还有哪些其他整洁的动画?是否可以模拟细胞自动机?
我看到一些选项:您可以使用列表,您可以使用向量,您可以使用元组,您可以使用带有 ax
和y
字段的自定义数据类型等。在大多数语言中,由于某些特定原因,一种方法优于另一种方法。例如,在 C++ 中,使用类的性能要高得多。
在 Haskell 中哪种语言方式被认为是做到这一点?
我正在使用一种翻译成JavaScript的语言.为了避免一些堆栈溢出,我通过将某些函数转换为for循环来应用尾调用优化.令人惊讶的是,转换并不比递归版本快.
http://jsperf.com/sldjf-lajf-lkajf-lkfadsj-f/5
递归版:
(function recur(a0,s0){
return a0==0 ? s0 : recur(a0-1, a0+s0)
})(10000,0)
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尾部调用优化后:
ret3 = void 0;
a1 = 10000;
s2 = 0;
(function(){
while (!ret3) {
a1 == 0
? ret3 = s2
: (a1_tmp$ = a1 - 1 ,
s2_tmp$ = a1 + s2,
a1 = a1_tmp$,
s2 = s2_tmp$);
}
})();
ret3;
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使用Google Closure Compiler进行一些清理之后:
ret3 = 0;
a1 = 1E4;
for(s2 = 0; ret3 == 0;)
0 == a1
? ret3 = s2 …
Run Code Online (Sandbox Code Playgroud) JSON.stringify显然不是节省空间的.使用Node.js序列化和存储float32array的最优雅方法是什么?
编辑:人们正在结束这个问题,原因包括"基于意见"和"对问题缺乏了解".我认真地相信第一个是missclick.对于第二个,也许这使得它更清楚:
var fs = require("fs");
var len = 1000*1000*10;
var big_array = new Float32Array(len);
for (var i=0; i<len; ++i)
big_array[i] = Math.random();
// OBVIOUSLY NOT SPACE EFFICIENT \/
fs.writeFileSync("big_array.json",JSON.stringify(big_array));
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它不是空间效率,因为你将数字表示为字符串,因此8字节浮点数将使用~20 utf8字符,这是一种浪费.问题是:如何以节省空间的方式存储阵列?
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