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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index a36b9691fb..d043852ac3 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -8123,6 +8123,32 @@ the second case, the resulting script contains a @code{(string-append @dots{})} expression to construct the file name @emph{at run time}. @end deffn +@deffn {Scheme Syntax} let-system @var{system} @var{body}@dots{} +@deffnx {Scheme Syntax} let-system (@var{system} @var{target}) @var{body}@dots{} +Bind @var{system} to the currently targeted system---e.g., +@code{"x86_64-linux"}---within @var{body}. + +In the second case, additionally bind @var{target} to the current +cross-compilation target---a GNU triplet such as +@code{"arm-linux-gnueabihf"}---or @code{#f} if we are not +cross-compiling. + +@code{let-system} is useful in the occasional case where the object +spliced into the gexp depends on the target system, as in this example: + +@example +#~(system* + #+(let-system system + (cond ((string-prefix? "armhf-" system) + (file-append qemu "/bin/qemu-system-arm")) + ((string-prefix? "x86_64-" system) + (file-append qemu "/bin/qemu-system-x86_64")) + (else + (error "dunno!")))) + "-net" "user" #$image) +@end example +@end deffn + @deffn {Scheme Syntax} with-parameters ((@var{parameter} @var{value}) @dots{}) @var{exp} This macro is similar to the @code{parameterize} form for dynamically-bound @dfn{parameters} (@pxref{Parameters,,, guile, GNU |