> > What is supposed to happen if in the running program a call into the >> > library performs (set! x 13)? >> > > The result is unspecified. It would probably be better > if we had specifically said so. Note even mutation of > non-exported top-level bindings is unspecified in the > presence of multiple library loadings. >
Related to this is one paragraph in 5.1: It says: *Import declarations and definitions cause bindings to be created in the global environment or modify the value ofexisting global bindings. The initial environment of a pro-gram is empty, so at least one import declaration is neededto introduce initial bindings.* First of all, when (outside of a REPL) is it possible for an import declaration to modify (the value) of existing global bindings? Is this a correct library? (import (scheme base)) (begin (define x 1)) (import (only (other-lib) x) Or does it count against the fact that an imported binding is not allowed to be redefined or mutated (although the identifier is not yet imported in the begin form)? In case, this library is allowed by the standard, the quoted paragraph from 5.1 as written means that the import declaration (import (only (other-lib) x)) modifies the value of x. But this won't work if an implementation is allowed to bind an imported identifier to the same location as the exported identifier is bound to, because this would change the location x is bound to and not the value of the location x is currently bound to. Marc
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