On 12/19/2012 07:29 AM, Edward Z. Yang wrote:
Excerpts from Adam Chlipala's message of Thu Nov 29 00:58:30 +0800 2012:
2.) Is it reasonable to support ad-hoc tags in the compiler, defined
by the user? Previously I proposed some tags as compiler patches, but
I realize this is inflexible. Instead, I would like to be able to
write a syntactic form similar to the basis library. Say:
tag audio : ...
I can support this easily with a small patch to allow tags to be defined
in FFI modules beside [Basis]. The core tags don't have actual
implementations anywhere, and it's easy to enable the same possibilities
for tags in further FFI modules. I.e., no need to define a C function
returning a string. (The identifier is used to figure out the tag name.)
Sound good?
This appears to be deficient in a few ways:
1. Some tags/attributes conflict with reserved keywords in Ur/Web
(e.g. name) so we need a way of using that is not reserved but
specifying the proper translation.
I grant you this one. Might be enough of a pain in the ass to put off
until someone requests it for a specific case. ;)
2. This doesn't allow us to add extra attributes to Ur/Web for existing
tags. Probably the easiest way to do that is use the translation
mechanism to allow "extended tags" which have different types but
translate into the same tag as some built-in.
This should already work. The same tag can be declared in multiple FFI
module interfaces, and they all compile to the same HTML. It is, of
course, necessary to explicitly [open] the module with the alternate tags.
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