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