[web-devel] Hamlet and functions that take multiple arguments

[Mark Bradley]

On Fri, Jul 23, 2010 at 7:31 PM, Michael Snoyman <michael at snoyman.com> wrote:
> It's true that it won't be a runtime hit at all, so the parsing complexity
> isn't a concern from that perspective. I *am* worried about making Hamlet
> too complicated however. Does anyone else out there have an opinion on this
> topic?
> Actually, using the new period-not-required syntax, your example could be
> rewritten:
> [$hamlet|^(template f) x^|]

i like that

> which is definitely easier on my eyes. However, that syntax would not be
> available in $forall, $maybe et al.

an interesting perspective of this would be to use syntax in the
forall to show that you are working with a list (not sure how this
could be extended for maybe et al.)
$forall [(map snd) tupleList] val

> Michael
> PS: I like your e-mail address.

Cheers,
Mark

>
> On Thu, Jul 22, 2010 at 1:49 PM, Mark Bradley <barkmadley at gmail.com> wrote:
>>
>> looking at the code it does appear that your grammar for ContentEmbed
>> objects could be extended to include lparen and rparen's.  I'm not
>> sure exactly how this would translate with the deref function in
>> Text.Hamlet.Quasi (i havent used template haskell before) but it looks
>> like it is entirely possible, meaning my example would become:
>>
>> fun f x = [$hamlet| ^(template.f).x^ |]
>>
>> and all is well.  you could add an encoding for this such as:
>>
>> template.f,x
>>
>> this would have the same effect as the $ function from regular haskell.
>>
>> the problem with that encoding is that is it less general than just
>> allowing parens and probably more error prone.
>>
>> the good thing about this is that it doesn't really matter how
>> complicated you make the encoding and parsing and haskell code
>> generation because it happens once at compile time.
>>
>> On Wed, Jul 21, 2010 at 2:41 PM, Michael Snoyman <michael at snoyman.com>
>> wrote:
>> >
>> >
>> > On Wed, Jul 21, 2010 at 4:17 AM, Mark Bradley <barkmadley at gmail.com>
>> > wrote:
>> >>
>> >> hamlet doesn't appear to support functions that take more than one
>> >> argument.
>> >>
>> >> i.e.
>> >>
>> >> fun f x = [$hamlet| ^template.f.x^ |]
>> >>
>> >> produces the call template (f x)
>> >>
>> >> is there some way to make hamlet produce (template f) x?
>> >
>> > Unfortunately not. It's not any *technical* limitation in Hamlet, just
>> > that
>> > I can't think of a good, intuitive syntax for it. The way that I work
>> > around
>> > this is by defining variables in a where clause, eg
>> > fun f x = [$hamlet|^templateTmp^|] where templateTmp = template f x
>> > If you have better ideas, I'm open to hearing them ;).
>> > Michael
>
>