C and C++: All other languages they support have a nice property - they're not architecture/platform dependent in ways that are often exposed to the user. Basically with all of them they can migrate from big-endian 32b environment to little-endian 64b environment and applications are very unlikely to get affected.

For coffeescript: you can use JS, so just compile before uploading. C#: they'd have to start using mono, or host on windows with .net - neither one may be a good solution for them.

When they added Java, they get Scala "for free" in a way. I don't think there's much difference in supporting architecture.

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