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Today's Topics:
1. manipulating Map for music application (Dennis Raddle)
----------------------------------------------------------------------
Message: 1
Date: Fri, 6 Nov 2015 22:07:47 -0800
From: Dennis Raddle <[email protected]>
To: Haskell Beginners <[email protected]>
Subject: [Haskell-beginners] manipulating Map for music application
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<CAKxLvopdv7q7gu3L4erohWf8Ssqw_x-2=qzzbmvruqdhigs...@mail.gmail.com>
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I have a Haskell program that computes music compositions. A composition
consists of sounds that happen at locations. A location is data type Loc.
At each location is a list of chords. A chord is data type Chord. Each
chord contains some chord-specific data and a list of notes. A note is data
type Note.
So we have
data Note = Note ...
data Chord = Chord ChordSpecificData [Note]
type Composition = Map Loc [Chord]
I would like to write a few different functions that operate over all the
notes.
The following function breaks out all the notes, tupling them with the
associated Locs and Chords:
compositionToList :: Composition -> [(Loc,Chord,Note)]
The following function transforms Notes, keeping only the Just results. If
a Chord gets all its notes eliminated, that Chord is removed. If a Loc has
all its Chords removed, that Loc is removed from the Map.
mapNotesMaybe :: (Loc -> Chord -> Note -> Maybe Note) -> Composition
-> Composition
Any advice for concise code appreciated.
Dennis
What's a concise way of doing this?
Another useful function would be used for mapping
Dennis
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