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Today's Topics:
1. Re: is this not a better way ? data structure (Roelof Wobben)
2. Re: manipulating Map for music application (Dennis Raddle)
3. Why does floor not consider its argument an Integral?
(Jeffrey Brown)
4. Re: Why does floor not consider its argument an Integral?
(Jeffrey Brown)
----------------------------------------------------------------------
Message: 1
Date: Sat, 7 Nov 2015 23:32:29 +0100
From: Roelof Wobben <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] is this not a better way ? data
structure
Message-ID: <[email protected]>
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Message: 2
Date: Sat, 7 Nov 2015 15:01:09 -0800
From: Dennis Raddle <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] manipulating Map for music
application
Message-ID:
<cakxlvoo0mdszufzhfrcyfdceahbdmkoy-2yqnw_kd8uzzw9...@mail.gmail.com>
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Thanks! I'm a Haskell beginner and will relish the opportunity to learn
more by studying your code.
On Sat, Nov 7, 2015 at 9:47 AM, Chadda? Fouch? <[email protected]>
wrote:
> Ooops forgot that Chords are not just lists of Notes :
>
> mapNotesMaybe f compo = mapMaybeWithKey go compo
> where
> go loc chords = mconcat . map (fmap (:[]) . gogo loc) $ chords
> gogo loc chord@(Chord d notes) = fmap (Chord d) . mconcat . map (fmap
> (:[]) . f loc chord) $ notes
>
> Le sam. 7 nov. 2015 ? 18:41, Chadda? Fouch? <[email protected]> a
> ?crit :
>
>> This is a bit tricky but mapMaybeWithKey is clearly the tool for the job :
>>
>> > mapMaybeWithKey :: (k -> a -> Maybe
>> <https://hackage.haskell.org/package/base-4.7.0.1/docs/Data-Maybe.html#t:Maybe>
>> b) -> Map
>> <https://hackage.haskell.org/package/containers-0.5.6.3/docs/Data-Map-Lazy.html#t:Map>
>> k a -> Map
>> <https://hackage.haskell.org/package/containers-0.5.6.3/docs/Data-Map-Lazy.html#t:Map>
>> k b
>>
>> So :
>>
>>
>> mapNotesMaybe :: (Loc -> Chord -> Note -> Maybe Note) -> Composition ->
>> Composition
>> mapNotesMaybe f compo = mapMaybeWithKey go compo
>> where
>> go loc chords = mconcat . map (gogo loc) $ chords
>> gogo loc chord = mconcat . map (fmap pure . f loc chord) $ chord
>>
>> This should work.
>>
>> --
>> Chadda?
>>
>>
>> Le sam. 7 nov. 2015 ? 07:07, Dennis Raddle <[email protected]> a
>> ?crit :
>>
>>> 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
>>>
>>> _______________________________________________
>>> Beginners mailing list
>>> [email protected]
>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>>>
>>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
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Message: 3
Date: Sat, 7 Nov 2015 22:14:58 -0800
From: Jeffrey Brown <[email protected]>
To: [email protected], The Haskell-Beginners Mailing List -
Discussion of primarily beginner-level topics related to Haskell
<[email protected]>
Subject: [Haskell-beginners] Why does floor not consider its argument
an Integral?
Message-ID:
<caec4ma3pajjfvdm2r+aqktawjgkcbm2-w6hb5ztcuemeqx5...@mail.gmail.com>
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Tidal [1] defines these data types:
type Time = Rational
type Arc = (Time, Time)
I want to write a function "splitMultiCycArc" which divides an Arc into
mostly-integer segments, so that, for instance,
splitMultiCycArc (0,1) = [(0,1)]
splitMultiCycArc (0,2) = [(0,1),(1,2)]
splitMultiCycArc (0,3) = [(0,1),(1,2),(2,3)]
splitMultiCycArc (1%2,2) = [(1%2,1),(1,2)]
splitMultiCycArc (1,5%2) = [(1,2),(2,5%2)]
I thought I had solved the problem with this code:
splitMultiCycArc:: Arc -> [Arc]
splitMultiCycArc (a,b) = let ceiling_ish = floor a + 1 in
if b <= a then []
else if b <= ceiling_ish then [(a,b)]
else (a,ceiling_ish) : splitMultiCycArc (ceiling_ish,b)
When I try to load that, I get this single error:
> :reload
[12 of 13] Compiling Sound.Tidal.JBB ( Sound/Tidal/JBB.hs, interpreted
)
Sound/Tidal/JBB.hs:16:44:
No instance for (Integral Time) arising from a use of ?floor?
In the first argument of ?(+)?, namely ?floor a?
In the expression: floor a + 1
In an equation for ?ceiling_ish?: ceiling_ish = floor a + 1
Failed, modules loaded: Sound.Tidal.Strategies, Sound.Tidal.Dirt,
Sound.Tidal.Pattern, Sound.Tidal.Stream, Sound.Tidal.Parse,
Sound.Tidal.Tempo, Sound.Tidal.Time, Sound.Tidal.Utils,
Sound.Tidal.SuperCollider, Sound.Tidal.Params, Sound.Tidal.Transition.
>
And yet under other conditions, "floor" is perfectly happy operating on a
Time value:
> let a = (1%2,1) :: Arc
> floor (fst a) + 1
1
>
[1] https://hackage.haskell.org/package/tidal
--
Jeffrey Benjamin Brown
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Message: 4
Date: Sat, 7 Nov 2015 23:10:17 -0800
From: Jeffrey Brown <[email protected]>
To: [email protected], The Haskell-Beginners Mailing List -
Discussion of primarily beginner-level topics related to Haskell
<[email protected]>
Subject: Re: [Haskell-beginners] Why does floor not consider its
argument an Integral?
Message-ID:
<caec4ma0y8y-h9+r3jznobfu5molz1erxewqhw7ihvtwqztt...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
I solved it. I was misreading the error report as being about the input to
floor, when the problem was the output of it. This code works:
splitArcAtIntegers:: Arc -> [Arc]
splitArcAtIntegers (a,b) = let
ceiling_ish = fromInteger $ (floor a) + 1
in if b <= a then []
else if b <= ceiling_ish then [(a,b)]
else (a,ceiling_ish) : splitArcAtIntegers (ceiling_ish,b)
On Sat, Nov 7, 2015 at 10:14 PM, Jeffrey Brown <[email protected]>
wrote:
> Tidal [1] defines these data types:
>
> type Time = Rational
> type Arc = (Time, Time)
>
> I want to write a function "splitMultiCycArc" which divides an Arc into
> mostly-integer segments, so that, for instance,
>
> splitMultiCycArc (0,1) = [(0,1)]
> splitMultiCycArc (0,2) = [(0,1),(1,2)]
> splitMultiCycArc (0,3) = [(0,1),(1,2),(2,3)]
> splitMultiCycArc (1%2,2) = [(1%2,1),(1,2)]
> splitMultiCycArc (1,5%2) = [(1,2),(2,5%2)]
>
> I thought I had solved the problem with this code:
>
> splitMultiCycArc:: Arc -> [Arc]
> splitMultiCycArc (a,b) = let ceiling_ish = floor a + 1 in
> if b <= a then []
> else if b <= ceiling_ish then [(a,b)]
> else (a,ceiling_ish) : splitMultiCycArc (ceiling_ish,b)
>
> When I try to load that, I get this single error:
>
> > :reload
> [12 of 13] Compiling Sound.Tidal.JBB ( Sound/Tidal/JBB.hs,
> interpreted )
>
> Sound/Tidal/JBB.hs:16:44:
> No instance for (Integral Time) arising from a use of ?floor?
> In the first argument of ?(+)?, namely ?floor a?
> In the expression: floor a + 1
> In an equation for ?ceiling_ish?: ceiling_ish = floor a + 1
> Failed, modules loaded: Sound.Tidal.Strategies, Sound.Tidal.Dirt,
> Sound.Tidal.Pattern, Sound.Tidal.Stream, Sound.Tidal.Parse,
> Sound.Tidal.Tempo, Sound.Tidal.Time, Sound.Tidal.Utils,
> Sound.Tidal.SuperCollider, Sound.Tidal.Params, Sound.Tidal.Transition.
> >
>
> And yet under other conditions, "floor" is perfectly happy operating on a
> Time value:
>
> > let a = (1%2,1) :: Arc
> > floor (fst a) + 1
> 1
> >
>
> [1] https://hackage.haskell.org/package/tidal
>
>
> --
> Jeffrey Benjamin Brown
>
--
Jeffrey Benjamin Brown
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