freeCodeCamp/guide/chinese/haskell/monad/index.md

title	localeTitle
Monad	单子

Monad Laws

数据类型必须满足3个法则才能被视为monad

也许莫纳德

justHead :: Maybe Char 
 justHead = do 
    (x:xs) <- Just "" 
    return x 

列出Monad

回归与纯粹的应用相同

实例Monad []在哪里
return x = [x]
xs >> = f = concat（map f xs）
失败_ = []