Karya, built on 2020-11-26T21:03:17 (patch 23b5be2d53a9e8e7d6136cda5aae2849abe5cded)
Safe HaskellNone




Support for rhythmic spelling in different meters.



data Meter Source #


Instances details
Eq Meter # 
Instance details

Defined in Perform.Lilypond.Meter


(==) :: Meter -> Meter -> Bool #

(/=) :: Meter -> Meter -> Bool #

Show Meter # 
Instance details

Defined in Perform.Lilypond.Meter


showsPrec :: Int -> Meter -> ShowS #

show :: Meter -> String #

showList :: [Meter] -> ShowS #

Pretty Meter # 
Instance details

Defined in Perform.Lilypond.Meter

Types.ToLily Meter # 
Instance details

Defined in Perform.Lilypond.Meter


to_lily :: Meter -> Text Source #

meter_nums :: Meter -> [Int] Source #

NonEmpty list of numerators. E.g. [2, 3] indicates 2+3.

measure_time :: Meter -> Types.Time Source #

Duration of a measure, in Time.

tie breaking

allowed_duration :: Bool -> Meter -> Types.Time -> Types.Time -> Types.NoteDuration Source #

Figure out how much time a note at the given position should be allowed before it must tie.

The heuristic is:

  • A binary meter is one whose numerator is a power of 2.
  • First, restrict the maximum allowed_time. For binary meters, this is up to the rank of the start point - 2, which means that if you start on an 8th note, you can span until the next half note. Compound meters are different because the rank divisions don't correspond to binary note divisions (e.g. 34 goes dotted half, quarter, 8th, etc., instead of 44's whole, half, quarter, etc.). So they only go up to the rank-1. This is winds up being too restrictive though, because it means that e.g. you could never span a quarter note if you start on an eighth, but 8 4 8 4 is a perfectly readable 3/4 bar. So the allowed duration is extended to twice the duration to the next rank-1 crossing, which allows 8 8~8 to become 8 4.
  • Next, if the allowed duration corresponds exactly to possible note duration, take that. This expresses that it's preferable to spell without a tie if you can. If it doesn't correspond to a note duration, then it has to be tied, and break on the place where it crosses the lowest rank.
  • Complex meters like 2+3/4 are treated as binary if you are in the binary part. TODO not yet

See NOTE [tie-breaking heuristic]