>>= 在纯脚本中是什么意思？

Question

我正在阅读 purescript wiki，发现以下部分用 >>= 解释了 do。

>>= 是什么意思？

Do notation

The do keyword introduces simple syntactic sugar for monadic expressions.

Here is an example, using the monad for the Maybe type:
 maybeSum :: Maybe Number -> Maybe Number -> Maybe Number 
 maybeSum a b = do   
     n <- a
     m <- b   
     let result = n + m   
     return result 
maybeSum takes two values of type Maybe Number and returns their sum if neither number is Nothing.

When using do notation, there must be a corresponding instance of the Monad type class for the return type. Statements can have the following form:

a <- x which desugars to x >>= \a -> ...

x which desugars to x >>= \_ -> ... or just x if this is the last statement.

A let binding let a = x. Note the lack of the in keyword.

The example maybeSum desugars to ::
 maybeSum a b =
   a >>= \n ->
     b >>= \m ->
       let result = n + m
       in return result

Answer 1

>>=是一个函数，仅此而已。它位于 Prelude 模块中，类型为 (>>=) :: forall m a b. (Bind m) => m a -> (a -> m b) -> m b，是 Bind 类型 class 的 bind 函数的别名。您可以在 this link, found in the Pursuit package index.

中找到 Prelude 模块的定义

这个和Haskell中的Monad类型class密切相关，比较容易找资源。关于这个概念有一个 famous question on SO，如果您希望提高对绑定函数的了解，这是一个很好的起点（如果您现在开始进行函数式编程，可以暂时跳过它）。

>>= 在纯脚本中是什么意思？

What does >>= mean in purescript?

purescript