Thanks Matthew and Joel,
* yes, I took the brackets literally - oops
* I know I could just skip the date thing, but where's the teaching moment
in that ....
... as shown by the fact that I'm still struggling:
* I've defined the "maybe-date" outside of the ◊(define latex-source
◊string-append{} loop. So that works.
* however,
◊when/splice[maybe-date]{
\date{◊(pubdate->english maybe-date)}}
gives me:
string-append: contract violation
expected: string?
given: '(@ "\\date{" "Saturday, February 20th, 2016" "}")
argument position: 74th
other arguments...:... [165 total] ...
I guess instead of a string I'm outputting "something" (a quote?) that's a
concatenation o strings ...
I thought I could convert this into a simple string by using symbol->string
but no joy.
I'm pretty sure I'm missing something obvious about lists and strings here,
but I can't figure out what ...
On Thursday, March 23, 2017 at 3:25:23 AM UTC+1, Joel Dueck wrote:
>
> 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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