* guix/monads.scm: Unexport 'lower-inputs' and 'derivation-expression'.
(text-file*): Add comment about the switch to 'gexp->derivation'.
(lower-inputs): Add comment about its doom.
(derivation-expression): Likewise.
* guix/gexp.scm (lower-inputs*): Rename to...
(lower-inputs): ... this. Update callers.
* tests/monads.scm (derivation-expression): New procedure.
* doc/guix.texi (The Store Monad): Use 'gexp->derivation' instead of
'derivation-expression'. Remove documentation of
'derivation-expression'.
* guix/ui.scm (read/eval): Use THE-ROOT-MODULE so that macros are
properly expanded.
* tests/guix-build.sh: Use 'gexp->derivation' instead of
'derivation-expression'.monads: Hide 'derivation-expression' and 'lower-inputs'.
* guix/gexp.scm: New file.
* tests/gexp.scm: New file.
* Makefile.am (MODULES): Add guix/gexp.scm.
(SCM_TESTS): Add tests/gexp.scm.
* doc/guix.texi (Derivations): Add #:inputs in 'derivation' example.
Mark 'build-expression->derivation' as deprecated, refer to
"G-Expressions". Remove paragraph about code strata.
(G-Expressions): New node.
Ludovic Courtès