[1] I am the creator of mustache.java
Plus there's the whole thing that ‘logic-less’ is a big white elephant: templates need logic, or they quickly become unmanageably bloated and un-DRY. Being able to iterate and conditionally branch are fundamentals essential to templating languages, and so whilst Mustache is an interesting starting point, it's usually not the best solution.
Of course, the one benefit Mustache does have is parsers in lots of languages, allowing you to share templates across client and server-side — it'd be great if somebody were to invest time in producing (say) a Ruby version of Walrus, as it looks like a very useful tool from reading through the docs.
Logic-less templates are a red herring and I cringe every time I enter a project where someone has drunken the Kool-Aid.
There's the rare fringe use-case where logic-less templates make sense, e.g. when you need to accept templates from untrusted sources (user editable) or when you really can re-use them across tiers to a significant degree.
In pretty much all projects neither is the case.
Instead, they quickly turn into a ball on a chain that constantly gets in the way and causes more problems than it solves.
This is my experience from encountering them in nearly a dozen projects and from having fallen for the temptation more than once myself.
Maybe I'm misunderstanding this, but you can do some fancy stuff with handlebars.js. You can 'foreach' through a json collection right in the template, 'if' 'else' statements and a whole whack of other cool little logic statements. So far I've not found anything I can't do in handlebars that I could do generating the page server side. Maybe I'm missing some more advanced cases or misunderstanding the term 'logic-less'?
As for bloated template code? I really don't know what you are talking about. Perhaps you just haven't seen well written mustache templates. My startup, Bagcheck, and Twitter (where I now work) have switched completely to Mustache. It really does work well if you use it properly.
How come? If your base HTML templates are say python or ruby templates they could be localized fine. And if the JSON content your parsing with Walrus comes from the same backend and is also localized where's the issue?
It's mustache with some view logic sugar which makes a lot of sense as far as i'm concerned and would allow your HTML templates to be mostly 'logic free'.
Contributions always welcome :)
The power of Mustache (and Handlebars) was that it forced you to write logic-less templates. There's just no way to express logic other than checks for existence of values. That means that you have a minimal language that every non-programmer [1] can understand. You can change templates without diving into a language. Walrus changes that to be a pretty much full featured template language with full view logic (hey, look, there's MATH methods in there). It perverts the idea of Mustache.
[1] aka designer or template-guru :)