Duration comparison and swinging MIDI output

[Christopher R. Maden]

The attached file is good enough for me.

It includes (duration-equals?) which may be of general interest.

It also includes the \sw function, which, given a sequence, returns two
tagged sequences:

  \sw {
    \relative c' {
      a'4 a8 b a fs e d |
    }
  }

becomes

  {
     \tag #'layout {
       \relative c' {
         a'4 a8 b a fs e d |
       }
     }
     \tag #'midi {
       \relative c' {
         a'4
         \times 2/3 a4 \times 2/3 b8
         \times 2/3 a4 \times 2/3 fs8
         \times 2/3 e4 \times 2/3 d8 |
       }
     }
  }

It can then be used with

 \keepWithTag #'layout \theTune
 \keepWithTag #'midi \theTune

Caveats:

1) The swung result is suitable for MIDI output, but not for print
layout; as it was done by tweaking internals, it lacks the proper
triplet brackets around the pairs of notes.

2) This is strictly sufficient to my needs.  In particular, \sw assumes
that its content is a relative sequence, and will produce odd results
otherwise.  It does work with chords, as long as all the notes in the
chord are the same duration.  It does not handle un-paired eighth notes.
 It probably handles eighth rests, but I haven’t checked yet.

If anyone wants to make this a more general and better utility, please
feel free.

~Chris
-- 
Chris Maden, text nerd  <URL: http://crism.maden.org/ >
Does this mean we can have our civil liberties back now?
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swing.ly
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