PHP

$ php -r '::'
Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM

WTF ? http://en.wikipedia.org/wiki/Scope_resolution_operator

为什么不说意外的T_SCOPE_RESOLUTION_OPERATOR ?

INTERCAL可能是最奇怪的语言特征的最佳汇编。我个人最喜欢的是COMEFROM语句，它(几乎)与GOTO相反。

COMEFROM is roughly the opposite of GOTO in that it can take the execution state from any arbitrary point in code to a COMEFROM statement. The point in code where the state transfer happens is usually given as a parameter to COMEFROM. Whether the transfer happens before or after the instruction at the specified transfer point depends on the language used. Depending on the language used, multiple COMEFROMs referencing the same departure point may be invalid, be non-deterministic, be executed in some sort of defined priority, or even induce parallel or otherwise concurrent execution as seen in Threaded Intercal. A simple example of a "COMEFROM x" statement is a label x (which does not need to be physically located anywhere near its corresponding COMEFROM) that acts as a "trap door". When code execution reaches the label, control gets passed to the statement following the COMEFROM. The effect of this is primarily to make debugging (and understanding the control flow of the program) extremely difficult, since there is no indication near the label that control will mysteriously jump to another point of the program.

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。

我一直是PHP错误的忠实粉丝，当在一行中使用两个冒号时脱离上下文:

解析错误:语法错误，第3行/path/to/file/error.php中的T_PAAMAYIM_NEKUDOTAYIM异常

第一次遇到这种情况时，我完全被弄糊涂了。

在我看来，在c#中能够将超出范围的整数转换为枚举是非常奇怪的。想象一下这个枚举:

enum Colour
{
    Red = 1,
    Green = 2,
    Blue = 3
}

现在，如果你写:

Colour eco;
eco = (Colour)17;

编译器认为这很好。还有运行时。

请看这里了解更多细节。

在Java中

String("aaa")==String("aaa") //false
//you need to use
String("aaa").equals(String("aaa")) // true