Re: \concat markup command

[Han-Wen Nienhuys]

Werner LEMBERG escreveu:
>>> Good question.  Perhaps `\concat { f i }' should be really
>>> identical to `fi', contrary to \line with word-space set to
>>> zero...
>> It's your call.  You could try to inspect the arguments, and if they
>> are strings or simple markups, concatenate the strings.
> 
> OK, here it is.  Please comment -- especially my Scheme code since I'm
> not really acquainted with it.

> #(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)
>     (do ((arg-list arg-list (cdr arg-list))
>          (result-list '() result-list)
>          (result #f (car result-list)))
>         ((null? arg-list) (reverse result-list))
>       (let ((arg (car arg-list)))
>         (if (and (pair? arg) (eqv? (car arg) simple-markup))
>           (set! arg (cadr arg)))
>         (if (and (string? result) (string? arg))
>             (set! result-list (cons (string-append result arg)
>                                     (cdr result-list)))
>           (set! result-list (cons arg result-list))))))


This is unschemey. I think it's better to use a
a functional approach. The signature should probably be something like

 (concat-string-args args-todo done)


and have a recursion 

 (concat-string-args (cdr args-todo)
                     (if (string? ..)
                         ..string-append onto (car done)..
                         (cons (car args-todo) done)))

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

-- 

Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen

LilyPond Software Design
 -- Code for Music Notation
http://www.lilypond-design.com