Add helpers 'getenv/list', 'setenv/list', 'setenv/list-extend', and
'setenv/list-delete' for list environment variables (such as search
* guix/build/utils.scm (getenv/list, setenv/list)
(setenv/list-extend, setenv/list-delete): New procedures.
* .dir-locals.el (scheme-mode): Indent them.
* tests/build-utils.scm ("getenv/list", "getenv/list: unset")
("setenv/list: ignore empty elements")
("setenv/list: unset if empty")
("setenv/list-extend: single element, prepend")
("setenv/list-extend: multiple elements, prepend")
("setenv/list-extend: multiple elements, append")
("setenv/list-delete: single deletion")
("setenv/list-delete: multiple deletions"): New tests.
I noticed that there are over 200 occurrences of this pattern in packages:
This patch introduces some helper procedures for these kinds of cases. With
this patch, instead of the above you could write:
(setenv/list-extend "PYTHONPATH" (getcwd))
Sometimes you want to add to the end of the path:
With this patch, you could write instead:
(setenv/list-extend "GEM_PATH" new-gem #:prepend? #f)
Adding include paths becomes much more readable in conjunction with
search-input-directory, with this:
(setenv/list-extend "CPATH"
(search-input-directory "/include/tirpc"))
A less common case, of removing a path:
(setenv/list-delete "CPLUS_INCLUDE_PATH"
(string-append gcc "/include/c++"))
(Bikeshed opportunity: I'm not in love with the names. I originally named
these 'setenv/path' rather than 'setenv/list', because I wanted to avoid
confusion with Guix's search paths, but I'm not sure 'setenv/list' is actually
I considered getenv*, setenv*, and so on, but I didn't think they were quite
I did consider 'setenv/list-extend!' and 'setenv/list-delete!' since they do
modify the env var in place, but "setenv" should already imply that.
Finally, it might be better to have e.g. 'setenv/path-prepend!' and
'setenv/path-append!' rather than the single 'setenv/path-extend', but I could
not settle on memorable, representative names. Using 'append' carries a
connotation that you are dealing with lists, because of 'append', but it also
accepts a single element. Using 'extend'/'prepend' together seems confusing
to me, because I might reach for 'extend' to add to the beginning of the list
if I forget about 'prepend'.)
guix/build/utils.scm | 56 +++++++++++++++++++++++++++++++++++++++++++
tests/build-utils.scm | 53 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 113 insertions(+)
Toggle diff (171 lines)
diff --git a/.dir-locals.el b/.dir-locals.el
index 919ed1d1c4..4b58220526 100644
(eval . (put 'add-before 'scheme-indent-function 2))
(eval . (put 'add-after 'scheme-indent-function 2))
+ (eval . (put 'setenv/list 'scheme-indent-function 1))
+ (eval . (put 'setenv/list-extend 'scheme-indent-function 1))
+ (eval . (put 'setenv/list-delete 'scheme-indent-function 1))
(eval . (put 'modify-services 'scheme-indent-function 1))
(eval . (put 'with-directory-excursion 'scheme-indent-function 1))
(eval . (put 'with-file-lock 'scheme-indent-function 1))
diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index 3beb7da67a..d0ac33a64f 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
;;; Copyright © 2020, 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
+;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
;;; This file is part of GNU Guix.
set-path-environment-variable
search-path-as-string->list
@@ -521,6 +527,56 @@ also be included. If FAIL-ON-ERROR? is true, raise an exception upon error."
+;;; Multiple-valued environment variables.
+(define* (setenv/list env-var lst #:key (separator #\:))
+ "Set environment variable ENV-VAR to the elements of LST separated by
+SEPARATOR. Empty elements are ignored. If ENV-VAR would be set to the empty
+ (let ((path (string-join (delete "" lst) (string separator))))
+ (if (string-null? path)
+ (setenv env-var path))))
+(define* (getenv/list env-var #:key (separator #\:))
+ "Return a list of the SEPARATOR-separated elements of environment variable
+ENV-VAR, or the empty list if ENV-VAR is unset."
+ (or (and=> (getenv env-var)
+ (cut string-split <> separator))
+(define* (setenv/list-extend env-var list-or-str
+ #:key (separator #\:) (prepend? #t))
+ "Add the element(s) LIST-OR-STR to the environment variable ENV-VAR using
+SEPARATOR between elements. Empty elements are ignored. Elements are placed
+at the beginning if PREPEND? is #t, or at the end otherwise."
+ (let* ((elements (match list-or-str
+ ((? string? str) (list str))
+ (original (or (getenv env-var) ""))
+ (path-list (if prepend?
+ (append elements (list original))
+ (cons original elements))))
+ (when (not (null? elements))
+ (setenv/list env-var path-list #:separator separator))))
+(define* (setenv/list-delete env-var list-or-str #:key (separator #\:))
+ "Remove the element(s) LIST-OR-STR from the SEPARATOR-separated environment
+variable ENV-VAR, and set ENV-VAR to that value. If ENV-VAR would be set to
+the empty string, unset ENV-VAR."
+ (let* ((elements (match list-or-str
+ ((? string? str) (list str))
+ (original (getenv/list env-var #:separator separator))
+ (path-list (lset-difference string=? original elements))
+ (path (string-join path-list (string separator))))
+ (if (string-null? path)
+ (setenv env-var path))))
diff --git a/tests/build-utils.scm b/tests/build-utils.scm
index 6b131c0af8..b26bffd9a8 100644
--- a/tests/build-utils.scm
+++ b/tests/build-utils.scm
;;; Copyright © 2019 Ricardo Wurmus <rekado@elephly.net>
;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
+;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
;;; This file is part of GNU Guix.
@@ -264,6 +265,58 @@ print('hello world')")) (get-string-all (current-input-port))))))))
+(test-equal "setenv/list: ignore empty elements"
+ (with-environment-variable "TEST_SETENV" #f
+ (setenv/list "TEST_SETENV" '("one" "" "three"))+ (getenv "TEST_SETENV")))
+(test-equal "setenv/list: unset if empty"
+ (with-environment-variable "TEST_SETENV" #f
+ (setenv/list "TEST_SETENV" '())
+ (getenv "TEST_SETENV")))
+(test-equal "getenv/list"
+ (with-environment-variable "TEST_SETENV" "one:two:three"
+ (getenv/list "TEST_SETENV")))
+(test-equal "getenv/list: unset"
+ (with-environment-variable "TEST_SETENV" #f
+ (getenv/list "TEST_SETENV")))
+(test-equal "setenv/list-extend: single element, prepend"
+ (with-environment-variable "TEST_SETENV" "one:two"
+ (setenv/list-extend "TEST_SETENV" "new")
+ (getenv "TEST_SETENV")))
+(test-equal "setenv/list-extend: multiple elements, prepend"
+ (with-environment-variable "TEST_SETENV" "one:two"
+ (setenv/list-extend "TEST_SETENV" '("first" "second"))+ (getenv "TEST_SETENV")))
+(test-equal "setenv/list-extend: multiple elements, append"
+ (with-environment-variable "TEST_SETENV" "one:two"
+ (setenv/list-extend "TEST_SETENV" '("first" "second") #:prepend? #f)+ (getenv "TEST_SETENV")))
+(test-equal "setenv/list-delete: single deletion"
+ (with-environment-variable "TEST_SETENV" "bad:one:two:bad:three:bad"
+ (setenv/list-delete "TEST_SETENV" "bad")
+ (getenv "TEST_SETENV")))
+(test-equal "setenv/list-delete: multiple deletions"
+ (with-environment-variable "TEST_SETENV" "bad:one:two:bad:three:bad"
+ (setenv/list-delete "TEST_SETENV" '("bad" "two"))+ (getenv "TEST_SETENV")))
(test-equal "search-input-file: exception if not found"
(file . "does-not-exist"))
base-commit: 693d75e859150601145b7f7303f61d4f48e76927