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

Michael Snoyman michael at snoyman.com
Fri Jul 23 05:31:44 EDT 2010

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

Actually, using the new period-not-required syntax, your example could be

[$hamlet|^(template f) x^|]

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


PS: I like your e-mail address.

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
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