In the demo he shows the basic running of the language. Then he shows it's realistic to write games in the language by running a space invaders like game. He then also shows the power of using the language as the pre-processor (very lisp like) in that he is able to run arbitrary code during the compilation process, such as checking that your printf statements have the proper number of arguments, or having it so you need kill so many space invaders or your compile fails. He also showed that it runs on linux as well as windows.
#run can run anything, if you don't trust the codebase you have to check everything for malicious calls. ( #run format c: as a joke :-/ when you compile )
check functions seem to have limited use. They can't check for input that isn't hardcoded( or can they? ). A runtime check might be more valuable.
I don't remember if it was mentioned; I think having C like implicit conversions is a bad idea. If types don't match exactly, cast or give an error.
defer is interesting, do you get an error if you try to return an object which is also defered getting deleted?
To clarify the probable mindset of the language designer: For games, runtime checks are pretty much useless - at runtime, the game is released and it's too late to do anything (ideally, discounting patches). So you want to catch everything you can at compile time. At the same time, performance is crucial. You need to be able to do everything the game needs to do within a 16ms time window. This means hardcoding / compiling in as many calculations as possible. Hence the focus on being able to do a lot at compile time.
That weakness already exists today in any project that relies on a build system (GNU Make, Autoconf, Ant/Maven, whatever), which is pretty much most of them.
That was just the first reaction I got, wow this can run anything.
> Do you really want a white paper?