- template engine – UI developers were furious with the template engine used in the previous project – freemarker, because it wasn’t null-safe – it blew up each time a chain of invocations had null. Play templates use scala, and so they are not null-safe. Scala has a different approach to nulls – Option, but third party libraries and our core code will be in Java and we’d have to introduce some null-to-Option conversion, and it will get ugly. This question shows a way to handle the case, but the comments make me hesitant to use it. That’s only part of the story – with all my respect and awe for static typing, the UI layer must use a simple scripting language. EL/JSTL is a good example. It doesn’t explode if it doesn’t find some value.
- static assets – this is hard, and I couldn’t find anything about using Play! with a CDN or how to merge multiple assets into one file. Is there an easy way to do that?
- IDE-support – the only was to edit the templates is through the scala editor, but it doesn’t have html support. This is not a deal-breaker, but tooling around the framework is a good thing to have.
- community – there is a good community around Play!, but I viewed it compared to grails. Play! is an older framework, and it has 2.5k questions on stackoverflow, while grails has 7.5k.
- module fragmentation – some of the important modules that I found were only for 1.x without direct replacements in 2.0.
- I won’t be working with it – UI developers will. Although I might be fine with all the type-safety and peculiar scala concepts, UI developers will probably not be.
- scala is ugly – now bash me for that. Yes, I’m not a Scala guy, but this being a highly upvoted answer kind of drove me off. It looks like a low-level programming language, and relevant to the previous point – it definitely doesn’t look OK to our UI developers.
- change of programming model – I mentioned the Option vs null, but there are tons of other things. This is not a problem of scala, of course, it even makes it the cool and good thing that has generated all the hype, but it’s a problem that too many people will have to switch their perspective at the same time
- we have been using Spring and Spring-MVC a lot, and Play’s integration with spring isn’t as smooth as that of Grails (which is built ontop of spring-mvc)
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