Matthew’s answer is great. I would just add that the main reason I made us
of dates in the metas was that I planned to have an RSS feed for chapters,
and things syndicated in a feed need to have a date stamp. But the feed is
also coded so as to omit anything that doesn’t have a 'doc-publish-date in
the metas.
So if you won’t be publishing an RSS feed, and if your book doesn’t
particularly need dates on each chapter, you could just remove any
reference to the date in the templates.
On Wednesday, March 22, 2017 at 12:20:29 AM UTC-5, Paul Atlan wrote:
>
> I'm slowly winding my way up the learning curve by adapting Joel Dueck's
> work to a personal web-book I want to write.
> I've hit a snag due to my limited understanding of racket, probably.
>
>
> The template.pdf.p files contains the following line to generate a nicely
> formatted LaTex date:
> \date{◊(pubdate->english (hash-ref metas 'doc-publish-date))}
>
> *metas *is generated from meta values in the source files, with one of
> the keys being "doc-publish-date".
>
> *pubdate->English * is a helper function to format everything nicely.
>
> This works perfectly if I don't forget the "doc-publish-date" key in the
> source files. If I do (or don't want to set it), the *hash-ref* fails and
> stops the rendering process.
>
> The *hash-ref* documentation (hash-ref
> <http://docs.racket-lang.org/reference/hashtables.html?q=hash-ref%20#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29>)
> mentions
> that one can write:
>
> hash-ref hash key [failure-result]
>
> were *failure-result* is either a procedure or is a value and gets
> returned instead of the missing key-value.
>
> I've been trying to use this in order to fail gracefully when
> *doc-publish-date
> *is missing:
> * either by returnnig a blank value (so the LaTex output will be " \date()
> "
> * or, even better, by skipping the whole \date function if the *hash-ref*
> function fails.
>
> Unfortunately all my efforts to set the failure-result have failed. I've
> tried e.g.
> \date{◊(pubdate->english (hash-ref metas 'doc-publish-date [] ))}
> in order to return an empty string, but racket chokes by telling me [] is
> not a procedure.
>
> And I can't find reference to something resembling if-error in the racket
> documentation.
>
> Any pointers would be greatly appreciated!
>
> P.
>
>
>
>
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