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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 38 |
1 files changed, 30 insertions, 8 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 9cb7ac53f9..e0a56a6bc0 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -7120,20 +7120,42 @@ optional dependency, you can define a variant that removes that dependency like so: @lisp -(use-modules (gnu packages gdb) ;for 'gdb' - (srfi srfi-1)) ;for 'alist-delete' +(use-modules (gnu packages gdb)) ;for 'gdb' (define gdb-sans-guile (package (inherit gdb) - (inputs (alist-delete "guile" - (package-inputs gdb))))) + (inputs (modify-inputs (package-inputs gdb) + (delete "guile"))))) @end lisp -The @code{alist-delete} call above removes the tuple from the -@code{inputs} field that has @code{"guile"} as its first element -(@pxref{SRFI-1 Association Lists,,, guile, GNU Guile Reference -Manual}). +The @code{modify-inputs} form above removes the @code{"guile"} package +from the @code{inputs} field of @code{gdb}. The @code{modify-inputs} +macro is a helper that can prove useful anytime you want to remove, add, +or replace package inputs. + +@deffn {Scheme Syntax} modify-inputs @var{inputs} @var{clauses} +Modify the given package inputs, as returned by @code{package-inputs} & co., +according to the given clauses. The example below removes the GMP and ACL +inputs of Coreutils and adds libcap to the back of the input list: + +@lisp +(modify-inputs (package-inputs coreutils) + (delete "gmp" "acl") + (append libcap)) +@end lisp + +The example below replaces the @code{guile} package from the inputs of +@code{guile-redis} with @code{guile-2.2}: + +@lisp +(modify-inputs (package-inputs guile-redis) + (replace "guile" guile-2.2)) +@end lisp + +The last type of clause is @code{prepend}, to add inputs to the front of +the list. +@end deffn In some cases, you may find it useful to write functions (``procedures'', in Scheme parlance) that return a package based on some |