My belated 2c (sorry, work has been keeping me away from things Yesod and Haskell):
1. The key reason I switched to Yesod was Hamlet. I'm very new to Haskell, and I wanted to try developing a webapp in it; when I looked at the various frameworks, my main question was "What will require me to learn the least new stuff, while still giving me a full Haskell-based development experience?" Yesod was the answer, because I was already familiar with Haml. So, it is one less thing a large swath of people need to learn when they decide to give Yesod a try. And at least in my case, it was a deciding factor.
2. I'm not convinced closeness to HTML is a design goal. My experience is again limited, but I wouldn't expect many people to switch existing projects to Yesod (or really, from any framework to any other); therefore, the idea that someone will have a bunch of HTML to be converted as simply as possible to whatever templating language we use seems remote.
3. Along the same lines, the reason for the existence of templating frameworks like Haml and Hamlet is precisely that people don't enjoy writing HTML: why would we constrain ourselves by similarity to something people have put large (and creative) amounts of effort into avoiding? I think it is unduly limiting.
4. I do believe there are some issues with Hamlet; in fact, the issues raised by Greg are exactly the issues I have. I don't see having a Yesod-specific templating language as the solution, unless this new syntax gives Yesod such a big productivity boost compared to using Hamlet that it's worth putting in the effort.
In brief, I think Hamlet is 95% of the way there, and that Michael has done a great job with it. It seems easier to take it another 4% and get it to 99% than it would be to rewrite the syntax from scratch. I don't view HTML similarity as a bonus (or a malus, either way). Maintaining (and furthering) similarity with Haml seems worthier goal, given how many people use it, are familiar with it, and love it; it will ease adoption.
I hope this all made sense, and that I didn't start an argument about bike shed colors... ;-)
Alexandros
On Sat, Dec 11, 2010 at 10:48 AM, Michael Snoyman
<michael@snoyman.com> wrote:
Alright, at this point I've only heard positive things about this
syntax change. Does anyone want to volunteer to try and tackle this,
or will this need to wait till I can get around to it? Fair warning:
I'm likely to try to deal with the WAI + enumerator and xml-enumerator
tasks first. If someone wants to take a crack at the Hamlet changes,
I'll be happy to review things.
Michael