[racket] Macro using eval inside html-template

My function would always get hung up on the unknown identifiers like 
'title' or 'math' when it tried to evaluate the expressions passed as 
arguments -
but you are right, the macro is not really necessary. I can quote the 
expressions and use the html-writing module instead, which handles 
quoted lists.
I was just looking for ways to achieve a cleaner syntax.



On 07.01.13 23:20, Matthias Felleisen wrote:
> I don't see any need for a macro here. Why not use a function that iterates over these 'forms':
>
> (define (expr-iter . form)
>    (for ((f form))
>      (case (first f)
>        ...
>        [(math) (eval (second f) some-useful-namespace)]
>        ...)))
>
>
>
>
>
> On Jan 7, 2013, at 3:57 PM, Philipp Dikmann wrote:
>
>> Hello Racket-Users,
>>
>> in trying to iterate a series of expressions and evaluating them differently on a case-by-case basis - specifically in the body of a (html-template) - Racket is throwing errors indicating that my expressions end up in the wrong places. In the code below, it appears that + is being interpreted as an HTML element name; am I messing up expansion time and run time?
>>
>>
>> #lang racket
>>
>> (require (planet neil/html-template:2:2))
>>
>> (define-syntax-rule (expr-iter form ...)
>>   (begin
>>     (case (car 'form)
>>       [(title) (display (cadr 'form))]
>>       [(math) (eval (cadr 'form))]
>>       [(html) (html-template
>>                (eval (cadr 'form)))]) ...))
>>
>> (expr-iter (title "sometitle")
>>            (math (+ 1 2))
>>            (html (p "hello")))
>>
>>
>> Best regards,
>> Philipp
>>
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