diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 3923627c79..6d3361878b 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -3985,7 +3985,7 @@ The @code{local-file}, @code{plain-file}, @code{computed-file}, these objects lead to a file in the store. Consider this G-expression: @example -#~(system* (string-append #$glibc "/sbin/nscd") "-f" +#~(system* #$(file-append glibc "/sbin/nscd") "-f" #$(local-file "/tmp/my-nscd.conf")) @end example @@ -4044,7 +4044,7 @@ command: (use-modules (guix gexp) (gnu packages base)) (gexp->script "list-files" - #~(execl (string-append #$coreutils "/bin/ls") + #~(execl #$(file-append coreutils "/bin/ls") "ls")) @end example @@ -4055,8 +4055,7 @@ executable file @file{/gnu/store/@dots{}-list-files} along these lines: @example #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds !# -(execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls") - "ls") +(execl "/gnu/store/@dots{}-coreutils-8.22"/bin/ls" "ls") @end example @end deffn @@ -4126,6 +4125,34 @@ as in: This is the declarative counterpart of @code{text-file*}. @end deffn +@deffn {Scheme Procedure} file-append @var{obj} @var{suffix} @dots{} +Return a file-like object that expands to the concatenation of @var{obj} +and @var{suffix}, where @var{obj} is a lowerable object and each +@var{suffix} is a string. + +As an example, consider this gexp: + +@example +(gexp->script "run-uname" + #~(system* #$(file-append coreutils + "/bin/uname"))) +@end example + +The same effect could be achieved with: + +@example +(gexp->script "run-uname" + #~(system* (string-append #$coreutils + "/bin/uname"))) +@end example + +There is one difference though: in the @code{file-append} case, the +resulting script contains the absolute file name as a string, whereas in +the second case, the resulting script contains a @code{(string-append +@dots{})} expression to construct the file name @emph{at run time}. +@end deffn + + Of course, in addition to gexps embedded in ``host'' code, there are also modules containing build tools. To make it clear that they are meant to be used in the build stratum, these modules are kept in the |