在Java中(这是一个导致赋值的if语句)

result = (Boolean condition) ? (if Boolean is true) : (if Boolean is false);

or

data Nat = Z|S Nat deriving Show
nattoInt Z = 0
nattoInt (S a) = 1 + nattoInt a

buildNat 0 = Z
buildNat a  =  S (buildNat (a - 1))

在Haskell…我仍然不太明白这是如何定义自然数的(我完全理解理论:-p)

在ruby/python/c中，你可以像这样连接字符串:

a = "foo" "bar"
print a # => "foobar"

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。

当今所有语言:

TypeA a = (TypeA)some_operation_returning_TypeB(1,2,3); // TypeB is not inheriting TypeA

在运行时失败，并带有"Cast to TypeA failed exception"-消息(或类似消息)。这告诉我们程序员到底有多懒。他们没有办法产生消息“未能将TypeA的变量‘a’与TypeB的值‘some_operation_returning_TypeB(1,2,3)’赋值”。他. .他们的座右铭是“犯错误的人必须受苦”。

在ColdFusion中，文本值自动转换为各种数据类型，用于各种目的。我遇到了一个奇怪的问题，“00A”和“000”被返回为相等。事实证明，ColdFusion将“00A”解释为时间，转换为某种数字时间格式，并将其转换为0。“000”被转换为0。所以它们都被认为是相等的。那时我学习了字符串的比较函数。

在javaScript中，NaN是一个全局变量。