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Alan Watson <a.watson@xxxxxxxxxxxxxxxx> writes: > (a) For my Scheme, I looked at the errors I wanted to signal and > decided that I only needed to deal with pairs, symbols, and nulls[*]. > I would be interested to hear why you might want to associate source > location with other types of object. For example to report that it obviously has a wrong type, in an implementation which tries to infer some types statically. E.g. (apply f 5). > (b) You can distinguish small integers by having interned small > integers be unboxed[**] and uninterned small integers be boxed. This complicates the implementation. It's silly to introduce non-canonical representation of integers just for this reason. In my toy Scheme implementation I already had a dynamically typed host language, so it would introduce a need of wrappers for some types like numbers, while they weren't needed before. > [**] Boxed small integers are not necessarily a serious performance > problem if you use a cache of very small integers. It's still some performance hit: - The cache is much smaller than the range of unboxed numbers - Reading the value has to dereference a pointer and use processor cache - There is no single representation used in various places where values are known to fit in a machine word, e.g. vector indices -- __("< Marcin Kowalczyk \__/ qrczak@xxxxxxxxxx ^^ http://qrnik.knm.org.pl/~qrczak/