@@ -4631,7 +4631,7 @@ but it supports the following options:
@itemx --branch=@var{branch}
Download code for the @code{guix} channel from the specified @var{url}, at the
given @var{commit} (a valid Git commit ID represented as a hexadecimal
-string), or @var{branch}.
+string or the name of a tag), or @var{branch}.
@cindex @file{channels.scm}, configuration file
@cindex configuration file for channels
@@ -4783,6 +4783,25 @@ of Guix to be used is defined by a commit or by a channel
description file created by @command{guix describe}
(@pxref{Invoking guix describe}).
+Let's assume that you want to travel to those days of November 2020 when
+version 1.2.0 of Guix was released and, once you're there, run the
+@command{guile} of that time:
+
+@example
+guix time-machine --commit=v1.2.0 -- \
+ environment -C --ad-hoc guile -- guile
+@end example
+
+The command above fetches Guix@tie{}1.2.0 and runs its @command{guix
+environment} command to spawn an environment in a container running
+@command{guile} (@command{guix environment} has since been subsumed by
+@command{guix shell}; @pxref{Invoking guix shell}). It's like driving a
+DeLorean@footnote{If you don't know what a DeLorean is, consider
+traveling back to the 1980's.}! The first @command{guix time-machine}
+invocation can be expensive: it may have to download or even build a
+large number of packages; the result is cached though and subsequent
+commands targeting the same commit are almost instantaneous.
+
The general syntax is:
@example
@@ -4799,7 +4818,7 @@ this revision are the same as for @command{guix pull} (@pxref{Invoking guix pull
@itemx --branch=@var{branch}
Use the @code{guix} channel from the specified @var{url}, at the
given @var{commit} (a valid Git commit ID represented as a hexadecimal
-string), or @var{branch}.
+string or the name of a tag), or @var{branch}.
@item --channels=@var{file}
@itemx -C @var{file}
@@ -248,7 +248,7 @@ (define (channel-reference channel)
'latest-repository-commit'."
(match (channel-commit channel)
(#f `(branch . ,(channel-branch channel)))
- (commit `(commit . ,(channel-commit channel)))))
+ (commit `(tag-or-commit . ,(channel-commit channel)))))
(define sexp->channel-introduction
(match-lambda
@@ -835,7 +835,7 @@ (define (channel-full-commit channel)
(branch (channel-branch channel)))
(if (and commit (commit-id? commit))
commit
- (let* ((ref (if commit `(commit . ,commit) `(branch . ,branch)))
+ (let* ((ref (if commit `(tag-or-commit . ,commit) `(branch . ,branch)))
(cache commit relation
(update-cached-checkout (channel-url channel)
#:ref ref