Re: New try with lyric extender

[David Kastrup]

Yann <address@hidden> writes:

> 2014-02-13 15:36 GMT+01:00 David Nalesnik <address@hidden>:
>> Hi Yann,
>>
>> Looks to be simply a problem with too many parentheses.
>> Try this:
>>
>>  \version "2.18.0"
>> correctionAlignement = ##t
>> aligner = \relative c' { g'4. g8 c,4( c) | }
>> lyric = \lyricmode { Glo -- ri -- a __ }
>>
>> <<
>>   \new Staff <<
>>     \new Voice = "melodie" \relative c'{ \voiceOne g'4. g8 c,2 | | }
>>     \new Voice = "alto" \relative c' { \voiceTwo c4 bes c2 | }
>>     #(cond ((eq? correctionAlignement #t)
>>       #{ \new NullVoice = "aligner" \aligner #}))
>>   >>
>>   #(if (eq? correctionAlignement #t)
>>        #{ \new Lyrics \lyricsto "aligner" $lyric #}
>>        #{ \new Lyrics \lyricsto "melodie" $lyric #})
>> >>
>>
>> HTH,
>> David
>
> Hi David, thank you very much for your almost instant answer :)
>
> Ah yes, it works. I didn't think too much parentheses could harm... Is
> it because they have some special meaning in scheme (evaluate this
> expression, or something like this) ?

Yes.  When an expression is read, () enclose a list.  When a list is
evaluated, its first element is the function to call and the remaining
elements (after evaluation for functions, before evaluation for macros)
are the arguments.

So + is a function, and (+) is 0, namely the addition function called on
zero arguments.  And ((+)) tries calling 0 as a function, but since it
is not a function, you get an error.

-- 
David Kastrup