25 lines
367 B
Markdown
25 lines
367 B
Markdown
---
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title: Monad
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localeTitle: 单子
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---
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# Monad Laws
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数据类型必须满足3个法则才能被视为monad
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# 也许莫纳德
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```haskell
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justHead :: Maybe Char
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justHead = do
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(x:xs) <- Just ""
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return x
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```
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# 列出Monad
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回归与纯粹的应用相同
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实例Monad \[\]在哪里
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return x = \[x\]
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xs >> = f = concat（map f xs）
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失败\_ = \[\] |