后端那些事 ---语言（Python）

静态语言，动态语言，弱类型语言，强类型语言

弱/强类型指的是语言类型系统的类型检查的严格程度。动/静指的是变量与类型的绑定方法

弱类型：

> "1"+2
'12'

强类型：

>>> "1"+2
Traceback (most recent call last):
  File "", line 1, in <module>
TypeError: cannot concatenate 'str' and 'int' objects

动态类型：

>>> a = 1
>>> type(a)
<type 'int'>
>>> a = "s"
>>> type(a)
<type 'str'>

静态类型：

Prelude> let a = "123" :: Int

<interactive>:2:9:
    Couldn't match expected type `Int' with actual type `[Char]'
    In the expression: "123" :: Int
    In an equation for `a': a = "123" :: Int