Beware of the Train

Further thoughts: the problem with Scheme is basically the same as the problem with Pascal. They're both great teaching languages, with simple, orthogonal cores that can be easily grasped by students, so they can concentrate on learning the actual material without getting distracted by learning all the weird exceptions and special cases. But, because they're intended for teaching, only the core is standardised. Lots of things which are crucial to practical programming but inessential for teaching are left out. Hence, any distribution that aspires to practicality has to make choices of what to do about the bits that aren't in the standard. This is particularly bad in Scheme's case, because it's designed to teach a class in programming language design and implementation - there's no standard module system, for instance (but plenty of advice on how to whip up your own out of lambdas...). This in turn makes it very hard to develop a standard library of code that's portable across distributions - everyone has their own idea of what a module is, or of how to talk to the operating system, etc.