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List: haskell-beginners
Subject: =?ISO-8859-1?Q?R=E9f=2E_=3A_[Haskell-beginners]_a_problem?=
From: corentin.dupont () ext ! mpsa ! com
Date: 2010-06-25 13:33:09
Message-ID: OFC3194BFC.B1AC7E8F-ONC125774D.004A3F7B-C125774D.004A7244 () mpsa ! com
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Hello,
I would do (not that concise):
toMaybe :: Music_Data_ -> (Maybe Note, Maybe Direction, Maybe Sound)
toMaybe (Music_Data_1 n) = (Just n, Nothing, Nothing)
toMaybe (Music_Data_4 d) = (Nothing, Just d, Nothing)
toMaybe (Music_Data_9 s) = (Nothing, Nothing, Just s)
catMaybes3 (a,b,c) = (catMaybes a, catMaybes b, catMaybes c)
sortOutMusicData :: [Music_Data_] -> ([Note],[Direction],[Sound])
sortOutMusicData = catMaybes3 . unzip3 . map toMaybe
Corentin
Michael Mossey
<mpm@alumni.calt
ech.edu> Pour
Envoyé par : beginners@haskell.org
beginners-bounce cc
s@haskell.org
Objet
[Haskell-beginners] a problem
23/06/2010 10:08
Can I get a suggestion for a concise way to write 'sortOutMusicData' as
described here? This is MusicXML-related.
data Music_Data_ = Music_Data_1 Note
| Music_Data_4 Direction
| Music_Data_9 Sound
...
sortOutMusicData :: [Music_Data_] -> ([Note],[Direction],[Sound])
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