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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 38 |
1 files changed, 37 insertions, 1 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index c9d9bd8977..b315325034 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -3697,6 +3697,30 @@ In the example above, the native build of @var{coreutils} is used, so that @command{ln} can actually run on the host; but then the cross-compiled build of @var{emacs} is referenced. +@cindex imported modules, for gexps +@findex with-imported-modules +Another gexp feature is @dfn{imported modules}: sometimes you want to be +able to use certain Guile modules from the ``host environment'' in the +gexp, so those modules should be imported in the ``build environment''. +The @code{with-imported-modules} form allows you to express that: + +@example +(let ((build (with-imported-modules '((guix build utils)) + #~(begin + (use-modules (guix build utils)) + (mkdir-p (string-append #$output "/bin")))))) + (gexp->derivation "empty-dir" + #~(begin + #$build + (display "success!\n") + #t))) +@end example + +@noindent +In this example, the @code{(guix build utils)} module is automatically +pulled into the isolated build environment of our gexp, such that +@code{(use-modules (guix build utils))} works as expected. + The syntactic form to construct gexps is summarized below. @deffn {Scheme Syntax} #~@var{exp} @@ -3756,6 +3780,16 @@ G-expressions created by @code{gexp} or @code{#~} are run-time objects of the @code{gexp?} type (see below.) @end deffn +@deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{} +Mark the gexps defined in @var{body}@dots{} as requiring @var{modules} +in their execution environment. @var{modules} must be a list of Guile +module names, such as @code{'((guix build utils) (guix build gremlin))}. + +This form has @emph{lexical} scope: it has an effect on the gexps +directly defined in @var{body}@dots{}, but not on those defined, say, in +procedures called from @var{body}@dots{}. +@end deffn + @deffn {Scheme Procedure} gexp? @var{obj} Return @code{#t} if @var{obj} is a G-expression. @end deffn @@ -3781,7 +3815,9 @@ stored in a file called @var{script-name}. When @var{target} is true, it is used as the cross-compilation target triplet for packages referred to by @var{exp}. -Make @var{modules} available in the evaluation context of @var{exp}; +@var{modules} is deprecated in favor of @code{with-imported-modules}. +Its meaning is to +make @var{modules} available in the evaluation context of @var{exp}; @var{modules} is a list of names of Guile modules searched in @var{module-path} to be copied in the store, compiled, and made available in the load path during the execution of @var{exp}---e.g., @code{((guix |