在你看来,你遇到过的最令人惊讶、最怪异、最奇怪或最“WTF”的语言特性是什么?
请每个回答只回答一个特征。
在你看来,你遇到过的最令人惊讶、最怪异、最奇怪或最“WTF”的语言特性是什么?
请每个回答只回答一个特征。
当前回答
叫/ cc。Call/cc将一个表示程序其余部分的函数传递给程序体。
其他回答
Haskell's use of Maybe and Just. Maybe a is a type constructor that returns a type of Just a, but Maybe Int won't accept just an Int, it requires it to be a Just Int or Nothing. So in essence in haskell parlance Just Int is about as much of an Int as an apple is an orange. The only connection is that Just 5 returns a type of Maybe Interger, which can be constructed with the function Just and an Integer argument. This makes sense but is about as hard to explain as it can theoretically be, which is the purpose of haskell right? So is Just really JustKindaLikeButNotAtAll yea sorta, and is Maybe really a KindaLooksLikeOrIsNothing, yea sorta again.
-- Create a function that returns a Maybe Int, and return a 5, which know is definitly Int'able
> let x :: Maybe Int; x = 5;
<interactive>:1:24:
No instance for (Num (Maybe Int))
arising from the literal `5' at <interactive>:1:24
Possible fix: add an instance declaration for (Num (Maybe Int))
In the expression: 5
In the definition of `x': x = 5
> Just 5
Just 5
it :: Maybe Integer
-- Create a function x which takes an Int
> let x :: Int -> Int; x _ = 0;
x :: Int -> Int
-- Try to give it a Just Int
> x $ Just 5
<interactive>:1:4:
Couldn't match expected type `Int' against inferred type `Maybe t'
In the second argument of `($)', namely `Just 5'
In the expression: x $ Just 5
In the definition of `it': it = x $ Just 5
祝你好运读到这篇文章,我希望它是正确的。
JavaScript中的变量赋值可以创建全局变量。如果一个变量在函数中被赋值,并且没有在相同的作用域中声明为var,那么它将隐式声明为global。
function foo() {
x = "juhu"; // creates a global variable x!
var y = "kinners"
}
foo();
alert(x); // alerts "juhu"
alert(y); // alerts undefined
注意,var语句也可以在给变量赋值后使用:
function foo() {
x = 12;
var x; // x is now local
return x;
}
alert(foo()); // will alert 12;
alert(x); // will alert undefined
我不敢相信这里还没有这个:JSF属性访问。
在JSF UI标签中,你可以将服务器端对象的属性值引用到接口中:
<h:inputText value="#{myObject.property}></h:inputText>
问题是Java不支持属性,所以你必须编写以get和set开头的方法,以便将UI对象链接到服务器上的“属性”。
public void setProperty(String property){...}
public String getProperty(){...}
当我第一次学习JSF时,这让我感到困惑,我仍然认为它值得使用wtf。尽管在Java实现对c#风格属性的支持之前,确实没有其他方法可以做到这一点。
通知7。一个有效程序的例子:
Chomsky is a room. A thought is a kind of thing. Color is a kind of value. The colors are red, green and blue. A thought has a color. It is usually Green. A thought can be colorful or colorless. It is usually colorless. An idea is a thought in Chomsky with description "Colorless green ideas sleep furiously." A manner is a kind of thing. Furiously is a manner. Sleeping relates one thought to one manner. The verb to sleep (he sleeps, they sleep, he slept, it is slept, he is sleeping) implies the sleeping relation. Colorless green ideas sleep furiously.
像图灵机模拟器这样的其他愚蠢的东西可以找到。
NSIS (Nullsoft Scriptable安装系统)有StrCmp指令:
StrCmp str1 str2 jump_if_equal [jump_if_not_equal] 比较str1和str2(不区分大小写)。如果str1和str2相等,则Gotos jump_if_equal,否则Gotos jump_if_not_equal。 StrCmp $0“一个字符串”0 +3 DetailPrint '$$0 == "a string"' 转到+ 2 DetailPrint '$$0 != "a string"'
锦上添花:jump_if_equal和jump_if_not_equal也可以是负数。但我猜你们已经从正数前面的+符号中算出来了。我不记得这是强制性的,还是只是一个可怕的惯例。
这基本上结合了最差的BASIC和最差的Assembler。