[web-devel] [hamlet] implicit spaces with newlines?

[Greg Weber]

The Yesod homepage looks like this:
        <p>
            If you are new to Yesod, you should start off with #
            <a href=@{FiveMinutesR}>the five minute start instructions
            . The #
            <a href=@{ScreencastsR}>screencasts
            \ give a nice introduction to some of the advanced concepts, and
#
            <a href=@{BookR}>the book
            \ is the recommended approach to learning Yesod. Ask the #
            <a href=@{CommunityR}>commnunity
            \ for help.

Allowing one-line tags in positions other than the very beginning allows for
the removal of the '#' character:
        <p>
            If you are new to Yesod, you should start off with
            \ <a href=@{FiveMinutesR}>the five minute start instructions
            . The <a href=@{ScreencastsR}>screencasts
            \ give a nice introduction to some of the advanced concepts, and
            \ <a href=@{BookR}>the book
            \ is the recommended approach to learning Yesod. Ask the
            \ <a href=@{CommunityR}>commnunity
            \ for help.

Having implicit spaces is actually a huge win here:
        <p>
            If you are new to Yesod, you should start off with
            <a href=@{FiveMinutesR}>the five minute start instructions
            The
            <a href=@{ScreencastsR}>screencasts
            give a nice introduction to some of the advanced concepts, and
            <a href=@{BookR}>the book
            is the recommended approach to learning Yesod. Ask the
            <a href=@{CommunityR}>commnunity
            for help.

But I am wondering if it is best to keep things the way they are but just
indicate when there should be implicit spaces. My thought is to somehow use
angle brackets. Changing <p> to <p>> would indicate implicit spaces.


Greg Weber

On Fri, May 20, 2011 at 8:22 AM, Patrick Brisbin <pbrisbin at gmail.com> wrote:

> On 05/20/11 at 11:12am, Daniel Patterson wrote:
> > I think what the original author was saying was that when you make a new
> line with html, whitespace is inserted, not whether hamlet should
> automatically insert space after every tag.
> >
> > So yes, writing <p>hello<strong>there</strong></p> should not put white
> spacing.
> >
> > But when you write, in html:
> > <p>hello
> >     <strong>there</strong></p>
> >
> > It is equivalent to <p>hello <strong>there</strong></p> (note the space).
>
> Isn't that simply due to the fact that HTML compresses whitespace across
> the board? (turning that "\n\t" or "\n    " into just " ")
>
> Leading spaces in hamlet are used to define nesting, so also compressing
> this whitespace (rather than stripping it) would produce odd effects:
>
>  <div>
>      <p>Hey
>          <strong>there
>
> Would turn into
>
>  <div> <p>Hey <strong>there</strong></p></div>
>
> Which has an unneeded space after the parent <div>
>
> Right?
>
> >
> >
> > On May 19, 2011, at 11:57 PM, Michael Snoyman wrote:
> >
> > > On Thu, May 19, 2011 at 11:49 PM, Patrick Palka <patrick at parcs.ath.cx>
> wrote:
> > >> I find it a bit unintuitive that the hamlet code
> > >>
> > >> <p>hello
> > >>    <strong>there
> > >>
> > >> or
> > >>
> > >> <p>
> > >>     hello
> > >>     <strong>there
> > >>
> > >> generates the html
> > >>
> > >> <p>hello<strong>there</strong></p>
> > >>
> > >> I expected there to be a space between "hello" and "there" similar to
> what
> > >> the html specifications dictate. Is this behavior intentional or an
> > >> oversight? If it's the former, then what is the recommended way to
> simulate
> > >> my expected behavior? Appending a space to the end of a line is
> > >> mentally ugly and syntactically obscure.
> > >
> > > I'm not sure what you mean by "what the html specifications dictate."
> > > HTML is whitespace-sensitive, meaning that:
> > >
> > >   <i>foo</i> <b>bar</b>
> > >
> > > and
> > >
> > >    <i>foo</i><b>bar</b>
> > >
> > > Are different. Now, in all likelihood in the above example, you will
> > > want to have the whitespace surrounding tags. But consider the
> > > following HTML:
> > >
> > >    <p>You are logged in as <i>Michael Snoyman</i>, <a
> > > href="/logout">logout</a>.</p><p>Another paragraph.</p>
> > >
> > > In the case of the <i> and <a> tags, we definitely do *not* want to
> > > add whitespace after the tag (though we do want it before the tag). In
> > > the case of <p>, we don't care one way or another, but adding the
> > > whitespace everywhere will take up (a trivial amount of) extra
> > > bandwidth. tl;dr: Sometimes you don't want the whitespace.
> > >
> > > So when designing Hamlet, I thought up a few possibilities:
> > >
> > > 1) What we do now: all whitespace must be explicit.
> > > 2) Implicitly add whitespace before/after every tag.
> > > 3) Do something "smart", adding whitespace where it's desired.
> > >
> > > (2) isn't really an option because it makes having a tag as the last
> > > word in a sentence impossible. (3) gives me the creeps: I like smart
> > > libraries, but I will *never* trust a library to do this kind of stuff
> > > correctly all the time, even if I'm the one making up the rules for it
> > > to follow! And I have no doubt that it will quickly devolve into 500
> > > lines of hairy code to try and cover millions of corner cases. Oh, and
> > > don't forget that there are other languages than English that might
> > > approach it differently.
> > >
> > > I suppose another possibility is (2) along with some special way of
> > > forcing the removal of extra whitespace, but this seemed much less
> > > intuitive than the current approach.
> > >
> > > Anyway, that's the reasoning behind this stuff, if people have better
> > > ideas, I'd like to hear them.
> > >
> > > Michael
> > >
> > > _______________________________________________
> > > web-devel mailing list
> > > web-devel at haskell.org
> > > http://www.haskell.org/mailman/listinfo/web-devel
> >
> >
> > _______________________________________________
> > web-devel mailing list
> > web-devel at haskell.org
> > http://www.haskell.org/mailman/listinfo/web-devel
>
> --
> patrick brisbin
>
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