15 lines
388 B
Markdown
15 lines
388 B
Markdown
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Example: List
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-------------
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- `[] :: * -> *` an <span class="yellow">Endofunctor</span>
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- \\(⊙:M×M→M\\) a nat. trans. (`join :: M (M a) -> M a`)
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- \\(η:I→M\\) a nat. trans.
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<pre class="haskell"><code>-- In Haskell ⊙ is "join" in "Control.Monad"
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join :: [[a]] -> [a]
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join = concat
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-- In Haskell the "return" function (unfortunate name)
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η :: a -> [a]
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η x = [x]</code></pre>
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