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Due to historical reasons, the code is in subfolder "1". With SVN removal, we place the code back and remove the annoying "1" folder.
74 lines
2.1 KiB
HTML
74 lines
2.1 KiB
HTML
<!doctype html>
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<title>CodeMirror: Haskell mode</title>
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<meta charset="utf-8"/>
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<link rel=stylesheet href="../../doc/docs.css">
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<link rel="stylesheet" href="../../lib/codemirror.css">
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<link rel="stylesheet" href="../../theme/elegant.css">
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<script src="../../lib/codemirror.js"></script>
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<script src="../../addon/edit/matchbrackets.js"></script>
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<script src="haskell.js"></script>
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<style type="text/css">.CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}</style>
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<div id=nav>
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<a href="http://codemirror.net"><img id=logo src="../../doc/logo.png"></a>
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<ul>
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<li><a href="../../index.html">Home</a>
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<li><a href="../../doc/manual.html">Manual</a>
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<li><a href="https://github.com/marijnh/codemirror">Code</a>
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</ul>
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<ul>
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<li><a href="../index.html">Language modes</a>
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<li><a class=active href="#">Haskell</a>
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</ul>
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</div>
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<article>
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<h2>Haskell mode</h2>
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<form><textarea id="code" name="code">
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module UniquePerms (
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uniquePerms
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)
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where
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-- | Find all unique permutations of a list where there might be duplicates.
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uniquePerms :: (Eq a) => [a] -> [[a]]
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uniquePerms = permBag . makeBag
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-- | An unordered collection where duplicate values are allowed,
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-- but represented with a single value and a count.
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type Bag a = [(a, Int)]
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makeBag :: (Eq a) => [a] -> Bag a
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makeBag [] = []
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makeBag (a:as) = mix a $ makeBag as
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where
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mix a [] = [(a,1)]
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mix a (bn@(b,n):bs) | a == b = (b,n+1):bs
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| otherwise = bn : mix a bs
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permBag :: Bag a -> [[a]]
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permBag [] = [[]]
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permBag bs = concatMap (\(f,cs) -> map (f:) $ permBag cs) . oneOfEach $ bs
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where
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oneOfEach [] = []
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oneOfEach (an@(a,n):bs) =
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let bs' = if n == 1 then bs else (a,n-1):bs
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in (a,bs') : mapSnd (an:) (oneOfEach bs)
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apSnd f (a,b) = (a, f b)
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mapSnd = map . apSnd
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</textarea></form>
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<script>
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var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
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lineNumbers: true,
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matchBrackets: true,
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theme: "elegant"
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});
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</script>
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<p><strong>MIME types defined:</strong> <code>text/x-haskell</code>.</p>
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</article>
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