[web-devel] [hamlet] implicit spaces with newlines?
Michael Snoyman
michael at snoyman.com
Tue May 24 08:13:49 CEST 2011
On Tue, May 24, 2011 at 7:00 AM, Greg Weber <greg at gregweber.info> wrote:
>
> 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.
What's the advantage of adding a new syntax for "implicit" space
versus just explicitly adding the space?
Michael
> 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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