hash/backslash confusion

[Mark Polesky]

Would anyone like to take a little time to look over this
highly confusing situation and try to explain to me why it
is this way?

I would find it quite helpful.

Thanks!
- Mark

\version "2.13.4"

% music expression variables can be defined with "=" or scheme-style,
% but all variable names must be entirely alphabetic.

sopranoMusic = \relative c'' { c8 d e d c2 }
#(define altoMusic #{ \relative e' { e8 f g f e2 } #})

% music expression variables can only be dereferenced with "\".

\score {
  \new Staff <<
  { \sopranoMusic }
  \\
  { \altoMusic }
  >>
}


% numeric variables can be defined with "=" or scheme-style, and
% scheme-defined numeric variable names *can* have non-alphabetic
% characters.

one = 1
hashTwo = #2
#(define scm-5 5)


% string variables can be defined with "=" or scheme-style, and
% scheme-defined string variable names can have hyphens, but not
% numbers!

quoteThree = "3"
hashQuoteFour = #"4"
#(define scm-quote-Six "6")


% regardless of the definition method, string variables can only be
% dereferenced with "\"; and numeric variables can only be dereferenced
% with "#"!

\markup \concat {
  \number \quoteThree    % string
  \hspace #one           % number
  \number \hashQuoteFour % string
  \hspace #hashTwo       % number
  \number \scm-quote-Six % string
  \hspace #scm-5         % number
  \number \hashQuoteFour % string
}

%% of course, these restrictions are not an issue within scheme code
#(for-each
   display
   (list one hashTwo quoteThree hashQuoteFour scm-5 scm-quote-Six))


%% now, neither of these will work
% \markup \concat { #3 #4 #6 }
% \markup \concat { #"3" #"4" #"6" }

%% but this will
\markup \concat { 3 4 6 }

%% and of course this will work
\markup \concat { "3" "4" "6" }

%% but strangely so will this
%% (note that \hashQuoteFour works, but not #"4")
\markup \concat { \quoteThree \hashQuoteFour \scm-quote-Six }


%% so these numbers must be internally represented as strings?
%% (since this does work)
\markup \concat { 3 4 6 }


%% there seems to be no way to successfully pass any of these to \markup
% \markup \concat { #one #hashTwo #scm-5 }


% So much confusion... any explanations appreciated!