Re: \concat markup command

[Werner LEMBERG]

> another option is to use fold-left or fold-right (srfi-1 IIRC) to do
> the list looping 

Ok, here's another try.  However, look how `result' is set in the
first `let' block -- what about adding safe-car and safe-cdr (on the
C++ level) which don't signal an error if its argument is the empty
list?  The Elisp versions of car and cdr do this by default...


    Werner

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#(define-markup-command (concat layout props args) (markup-list?)
  "Concatenate @var{args} in a horizontal line, without spaces inbetween.
Strings and simple markups are concatenated on the input level, allowing
ligatures.  For example, @code{\\concat @{ \"f\" \\simple #\"i\" @}} is
equivalent to @code{\"fi\"}."

  (define (concat-string-args arg-list)
    (fold-right (lambda (arg result-list)
                  (let ((result (if (pair? result-list)
                                    (car result-list)
                                  '())))
                    (if (and (pair? arg) (eqv? (car arg) simple-markup))
                      (set! arg (cadr arg)))
                    (if (and (string? result) (string? arg))
                        (cons (string-append arg result) (cdr result-list))
                      (cons arg result-list))))
                '()
                arg-list))

  (interpret-markup layout
                    (prepend-alist-chain 'word-space 0 props)
                    (make-line-markup (concat-string-args args))))


\relative {
  c-\markup { \concat { "f" "i" } \concat { "f" \null "i" } }
  c-\markup { \concat { "j" } }
  c-\markup { \concat { \tiny { "k" } } }
  c-\markup { \concat { "f" \simple #"i" } }
}