[lucianof]

For web apps I would like a language that works both compiled and not compiled. Either I just copy my scripts to the web server when I'm lazy (or developing), or I compile it (and run unit and integration tests and whatever) when I'm done developing. Is there any language/platform that works like that?

[tmhedberg]

The Snap framework (http://snapframework.com/) for Haskell works this way. Your application (including the web server itself) gets compiled down to a single binary, but during development you can make changes and see them reflected on the fly without manually recompiling. This is my understanding based on an interview with one of the framework's developers; I haven't used it myself for any significant project, though I plan to.

Haskell in general meets a lot (though probably not all) of the author's requirements. Static type inference is great, and Haskell's system makes explicit type declarations completely optional except for in a handful of rare cases, though you will find yourself wanting to use them on most functions anyway because of how they clarify and improve the readability of your code. Testing is also dead simple with tools like QuickCheck--it essentially manufactures test cases for you based on invariants that you specify about your code.

[microtonal]

I use Snap on one small project, it is pretty awesome. Snap applications have the terseness and simplicity of, say Sinatra or Rails, but with type checking. As is often the case in Haskell, if your program compiles it is usually correct.

What I also like about Snap (and Yesod) is that it is integrated well with the enumerator package. Simply said, the enumerator package allows you to implement composable data sources, manipulators, and sinks. Since many web applications consist of extracting data from a source, manipulating, and sending it, it allows you to write applications short and simple.

[lobster_johnson]

Looked briefly at Snap, but without something like HAML (http://haml-lang.com/) and SASS (http://sass-lang.com/) it's not something I will use. Not going back to the stone age of writing XML-with-expansions templates ever again.

[lucianof]

Thanks for the link, I'll have to check this out some time. For some reason I always find it hard to imagine how I could write a whole app in a functional language. Probably that's because I've never actually done it..