\version "2.19.10"

% Create a new xxxStaff and xxxVoice contexts with specified settings,
% derived from specified yyyStaff and yyyVoice contexts.
%
% TODO: instead of having 3 arguments: (parentstaff, parentvoice, parentname)
% the function should take just parentname and get parentstaff and parentvoice
% from that.
newLayoutInstrument =
#(define-scheme-function
  (parser location name parentstaff parentvoice parentname grouping staffsettings voicesettings)
  (string? ly:context-def? ly:context-def? string? ly:context-def? ly:context-mod? ly:context-mod?)
  (let ((staffname (string-append name "Staff"))
        (voicename (string-append name "Voice"))
        (parentstaffname (string-append parentname "Staff"))
        (parentvoicename (string-append parentname "Voice")))
    #{
      \layout {
        \context {
          #grouping
          \accepts #staffname
        }
        \context {
          #parentstaff
          \name #staffname
          \alias #parentstaffname
          \accepts #voicename % is it possible to make it accept Voices of derived instruments?
          \defaultchild #voicename

          #staffsettings
        }
        \context {
          #parentvoice
          \name #voicename
          \alias #parentvoicename

          #voicesettings
        }
      }
    #}))

% UGH!!! CODE DUPLICATION!!!
% This function is almost identical to the one above - obviously, they should be merged,
% but I didn't yet find a way to put both \layout and \midi stuff into one function :(
newMidiInstrument =
#(define-scheme-function
  (parser location name parentstaff parentvoice parentname grouping staffsettings voicesettings)
  (string? ly:context-def? ly:context-def? string? ly:context-def? ly:context-mod? ly:context-mod?)
  (let ((staffname (string-append name "Staff"))
        (voicename (string-append name "Voice"))
        (parentstaffname (string-append parentname "Staff"))
        (parentvoicename (string-append parentname "Voice")))
    #{
      \midi {
        \context {
          #grouping
          \accepts #staffname
        }
        \context {
          #parentstaff
          \name #staffname
          \alias #parentstaffname
          \accepts #voicename
          \defaultchild #voicename

          #staffsettings
        }
        \context {
          #parentvoice
          \name #voicename
          \alias #parentvoicename

          #voicesettings
        }
      }
    #}))


% define "instruments" - one generic and another one derived:

\layout {
  \newLayoutInstrument "Vocal" \Staff \Voice "" \ChoirStaff
  \with {
    \consists "Ambitus_engraver"
    instrumentName = "Vocals"
    shortInstrumentName = "Voc."
    \dynamicUp
    \tupletUp
  }
  \with { }
}
\midi {
  \newMidiInstrument "Vocal" \Staff \Voice "" \ChoirStaff
  \with {
    \remove "Staff_performer"
  }
  \with {
    \consists "Staff_performer"
    midiInstrument = "voice oohs"
  }
}

\layout {
  \newLayoutInstrument "Soprano" \VocalStaff \VocalVoice "Vocal" \ChoirStaff
  \with {
    instrumentName = "Soprano"
    shortInstrumentName = "S"
    \clef G
  }
  \with { }
}
\midi {
  \newMidiInstrument "Soprano" \VocalStaff \VocalVoice "Vocal" \ChoirStaff
  \with { }
  \with { }
}


% test:

\score {
  \new SopranoVoice \relative f' {
    c f c' f
  }
  \layout {
    \override Staff.Stem.thickness = 4
    \override VocalStaff.Stem.color = #blue
    \override SopranoVoice.NoteHead.color = #green
  }
  \midi {
    \set SopranoVoice.midiInstrument = "clarinet"
  }
}