* guix/gexp.scm (<gexp>)[natives]: New field.
(write-gexp): Use both 'gexp-references' and
'gexp-native-references'.
(gexp->derivation): Use both 'gexp-inputs' and 'gexp-native-inputs',
and append them.
(gexp-inputs): Add 'references' parameter and honor it.
(gexp-native-inputs): New procedure.
(gexp->sexp)[reference->sexp]: Add 'native?' parameter and honor it.
Use it, and use 'gexp-native-references'.
(gexp)[collect-native-escapes]: New procedure.
[escape->ref]: Handle 'ungexp-native' and 'ungexp-native-splicing'.
[substitute-ungexp, substitute-ungexp-splicing]: New procedures.
[substitute-references]: Use them, and handle 'ungexp-native' and
'ungexp-native-splicing'.
Adjust generated 'make-gexp' call to provide both normal references
and native references.
[read-ungexp]: Support 'ungexp-native' and
'ungexp-native-splicing'.
Add reader extension for #+.
* tests/gexp.scm (gexp-native-inputs): New procedure.
(gexp->sexp*): Add 'target' parameter.
("ungexp + ungexp-native",
"input list + ungexp-native",
"input list splicing + ungexp-native-splicing",
"gexp->derivation, ungexp-native",
"gexp->derivation, ungexp + ungexp-native"): New tests.
("sugar"): Add tests for #+ and #+@.
* doc/guix.texi (G-Expressions): Document 'ungexp-native' et al.
667b250846