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authorLudovic Courtès <ludo@gnu.org>2021-06-16 23:52:42 +0200
committerLudovic Courtès <ludo@gnu.org>2021-07-11 00:49:14 +0200
commit04b2f3dd80aa4a138e93a6a4a209c1beac5fca88 (patch)
tree6d703142a3f6c7fd1eb82d6cd31581f7e4335850 /doc
parentba32f6363878165b3ca53113f6c95b8677b8537b (diff)
packages: Add 'modify-inputs'.
* guix/packages.scm (inputs-sans-labels, replace-input): New procedures. (prepend, replace, modify-inputs): New macros. * doc/guix.texi (Defining Package Variants): Document 'modify-inputs'. * dir-locals.el: Add 'modify-inputs' and its keywords.
Diffstat (limited to 'doc')
-rw-r--r--doc/guix.texi38
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