On Fri, 03 Jul 2015 12:15:32 +0300, Anton Vodonosov said:
Envelope-From: avodonosov@yandex.by
A note about "philosophical problems" - if one wants to build a compact mental model, reasonable and consistent with all the Common Lisp properties, there probably may be more than one way to do so, and neither of possible models can be proven incorrect.
03.07.2015, 11:16, "Anton Vodonosov" avodonosov@yandex.ru:
I personally don't think that name CL-USER::FOO anyhow represents the "nature" of the symbol
The same number may be referenced as #x20000000 and as 536870912. It's just a way to refer the object, not the object itself.
I want to correct myself. Unlike numbers or any other objects, symbols _are_ about names, so we can say that the name CL-USER::FOO represents the "nature" of symbol.
I think Common Lisp wants to save memory and speedup comparison, so when we use the same name we get the same object, as implemented by INTERN (this trick even has name - the Flyweight pattern).
So, this is just an optimization trick, and UNITERN is a maintenance, system tool, not designed to express programs. We are encouraged to operate as if the symbol name means the same object.
I disagree about it being to save memory -- a CL symbol is an object with mutable attributes, so identity is important. Also, the identity of uninterned symbols is just as important (e.g. for macros) as interned ones, so finding symbols via packages (and the reader) is not fundamental to their common use.
Packages are just a way to convert strings to symbols, which is useful when they are obtained from files outside a running CL (e.g. via the reader/fasl loader).