Am Mo., 22. Juli 2024 um 20:47 Uhr schrieb Maxime Devos < maximede...@telenet.be>:
> > [...] > > > > > >In what kind of situation might a library name be made up of identifiers > (syntax objects) that might need to carry lexical information? > > > > As implied by the previous: never (in Guile, and probably most others). > > > > The only exception I can think of, is if: > > > > * ‘define-library’/’library’ is implemented as a macro (this is not part > of RnRS, but AFAIK neither is it against the standard) > > * hence, you can define a module from within another module (might be > situationally useful, but comes with new difficulties for module lookup) > > * there are multiple module namespaces > > * to determine which module namespace to put the module in, > ‘define-library’ uses lexical information > > * in particular, it uses components of the name of the library for lexical > information, even though there are other options like using the _*whole*_ > name (i.e., (foo bar) itself instead of ‘foo’ or ‘bar’). > > > > That’s a lot of ifs, and even then identifiers aren’t necessary, since > (AFAIK) the name (foo bar) itself carries lexical information (not sure). > > > > I’ve been assuming that numbers (in syntax) (say, #'3) don’t carry lexical > info, but since ‘syntax numbers’ carry file name+position information, it’s > not much of a stretch to potentially also include lexical information, so > perhaps numbers would work just fine too! (Implementation-dependent, but > ‘multiple module namespaces’ and ‘define-library as a macro’ are also > implementation-dependent.) > This would need a redefinition of what a syntax object is (see the R6RS). In principle, this would be possible, but the result would be incompatible with the R6RS. In R6RS, a macro transformer is allowed to output raw numbers; this would not be allowed in a hypothetical Scheme version that assumes that numbers necessarily carry a wrap (as identifiers do in the R6RS). Source location information is not mandatory information for the expander, so this reasoning does not apply here. Marc
