music-parts-1.3: src/Music/Parts.hs

module Music.Parts where
    
{-
    ## Terminology: Voice vs Part
    
    A voice is a container of notes (non-overlapping)
    
    A part is an identifier for a set of singers/musicians AND all the notes in a score
    designated for this set of performers. Part extraction has the type
    
        extractParts :: HasPart a => Score a -> [Score a]
    
    I.e. in a score for piano and ensemble, certain notes may be *in the piano part*, i.e.
    designated for the piano. Typically, a part is monophonic or polyphonic. A monophonic
    part is a voice, i.e.

        -- | Are there overlapping notes?
        isMonophonic :: Score a -> Bool

        -- | Fails for polyphonic scores.
        scoreToVoice :: Score a -> Voice (Maybe a)
    
    A polyphonic part contains several voices, i.e.

        scoreToVoices :: Score a -> [Voice (Maybe a)]  


    A part is any type a that satisfies (Ord a, Show a).
    Optionally, we may add a contraint (HasPartName a), i.e.

        class HasPartName a where
            partName :: a -> String
            partAbbr :: a -> String
    
    
    These contraints are used when printing scores (to get the order of the parts and their name).

        Vln1, Vln2 etc.

    Often we want to group parts, i.e.

        Chorus {
            Sop  { Sop1 Sop2 }
            Alto { Alto1 Alto2 }
            Ten  { Ten1 Ten 2 }
            Bass { Bass1 Bass2 }
        }
        Orchestra {
            Woodwinds { ... }
            Brass { ... }
            Perc { ... }
            Strings { ... }
        }


    isInGroup :: Group -> Part -> Bool
    partGroups :: Part -> [Group]


    partGroup :: (Part -> [Group] -> a) -> Group -> a
    tree :: (a -> [Tree a] -> b) -> Tree a -> b
    
    
    data MyPart
        = Fl
        | Sop
        | Vl1
        | Vl2
        | Pno

-}