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diff --git a/doc/guix.texi b/doc/guix.texi index b925485be5..76ec718b07 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -147,6 +147,7 @@ Package Management * Invoking guix gc:: Running the garbage collector. * Invoking guix pull:: Fetching the latest Guix and distribution. * Channels:: Customizing the package collection. +* Inferiors:: Interacting with another revision of Guix. * Invoking guix describe:: Display information about your Guix revision. * Invoking guix pack:: Creating software bundles. * Invoking guix archive:: Exporting and importing store files. @@ -1699,6 +1700,7 @@ guix package -i emacs-guix * Invoking guix gc:: Running the garbage collector. * Invoking guix pull:: Fetching the latest Guix and distribution. * Channels:: Customizing the package collection. +* Inferiors:: Interacting with another revision of Guix. * Invoking guix describe:: Display information about your Guix revision. * Invoking guix pack:: Creating software bundles. * Invoking guix archive:: Exporting and importing store files. @@ -3053,6 +3055,135 @@ package it defines. This gives you super powers, allowing you to track the provenance of binary artifacts with very fine grain, and to reproduce software environments at will---some sort of ``meta reproducibility'' capabilities, if you will. +@xref{Inferiors}, for another way to take advantage of these super powers. + +@node Inferiors +@section Inferiors + +@c TODO: Remove this once we're more confident about API stability. +@quotation Note +The functionality described here is a ``technology preview'' as of version +@value{VERSION}. As such, the interface is subject to change. +@end quotation + +@cindex inferiors +@cindex composition of Guix revisions +Sometimes you might need to mix packages from the revision of Guix you're +currently running with packages available in a different revision of Guix. +Guix @dfn{inferiors} allow you to achieve that by composing different Guix +revisions in arbitrary ways. + +@cindex inferior packages +Technically, an ``inferior'' is essentially a separate Guix process connected +to your main Guix process through a REPL (@pxref{Invoking guix repl}). The +@code{(guix inferior)} module allows you to create inferiors and to +communicate with them. It also provides a high-level interface to browse and +manipulate the packages that an inferior provides---@dfn{inferior packages}. + +When combined with channels (@pxref{Channels}), inferiors provide a simple way +to interact with a separate revision of Guix. For example, let's assume you +want to install in your profile the current @code{guile} package, along with +the @code{guile-json} as it existed in an older revision of Guix---perhaps +because the newer @code{guile-json} has an incompatible API and you want to +run your code against the old API@. To do that, you could write a manifest for +use by @code{guix package --manifest} (@pxref{Invoking guix package}); in that +manifest, you would create an inferior for that old Guix revision you care +about, and you would look up the @code{guile-json} package in the inferior: + +@lisp +(use-modules (guix inferior) (guix channels) + (srfi srfi-1)) ;for 'first' + +(define channels + ;; This is the old revision from which we want to + ;; extract guile-json. + (list (channel + (name 'guix) + (url "https://git.savannah.gnu.org/git/guix.git") + (commit + "65956ad3526ba09e1f7a40722c96c6ef7c0936fe")))) + +(define inferior + ;; An inferior representing the above revision. + (inferior-for-channels channels)) + +;; Now create a manifest with the current "guile" package +;; and the old "guile-json" package. +(packages->manifest + (list (first (lookup-inferior-packages inferior "guile-json")) + (specification->package "guile"))) +@end lisp + +On its first run, @command{guix package --manifest} might have to build the +channel you specified before it can create the inferior; subsequent runs will +be much faster because the Guix revision will be cached. + +The @code{(guix inferior)} module provides the following procedures to open an +inferior: + +@deffn {Scheme Procedure} inferior-for-channels @var{channels} @ + [#:cache-directory] [#:ttl] +Return an inferior for @var{channels}, a list of channels. Use the cache at +@var{cache-directory}, where entries can be reclaimed after @var{ttl} seconds. +This procedure opens a new connection to the build daemon. + +As a side effect, this procedure may build or substitute binaries for +@var{channels}, which can take time. +@end deffn + +@deffn {Scheme Procedure} open-inferior @var{directory} @ + [#:command "bin/guix"] +Open the inferior Guix in @var{directory}, running +@code{@var{directory}/@var{command} repl} or equivalent. Return @code{#f} if +the inferior could not be launched. +@end deffn + +@cindex inferior packages +The procedures listed below allow you to obtain and manipulate inferior +packages. + +@deffn {Scheme Procedure} inferior-packages @var{inferior} +Return the list of packages known to @var{inferior}. +@end deffn + +@deffn {Scheme Procedure} lookup-inferior-packages @var{inferior} @var{name} @ + [@var{version}] +Return the sorted list of inferior packages matching @var{name} in +@var{inferior}, with highest version numbers first. If @var{version} is true, +return only packages with a version number prefixed by @var{version}. +@end deffn + +@deffn {Scheme Procedure} inferior-package? @var{obj} +Return true if @var{obj} is an inferior package. +@end deffn + +@deffn {Scheme Procedure} inferior-package-name @var{package} +@deffnx {Scheme Procedure} inferior-package-version @var{package} +@deffnx {Scheme Procedure} inferior-package-synopsis @var{package} +@deffnx {Scheme Procedure} inferior-package-description @var{package} +@deffnx {Scheme Procedure} inferior-package-home-page @var{package} +@deffnx {Scheme Procedure} inferior-package-location @var{package} +@deffnx {Scheme Procedure} inferior-package-inputs @var{package} +@deffnx {Scheme Procedure} inferior-package-native-inputs @var{package} +@deffnx {Scheme Procedure} inferior-package-propagated-inputs @var{package} +@deffnx {Scheme Procedure} inferior-package-transitive-propagated-inputs @var{package} +@deffnx {Scheme Procedure} inferior-package-native-search-paths @var{package} +@deffnx {Scheme Procedure} inferior-package-transitive-native-search-paths @var{package} +@deffnx {Scheme Procedure} inferior-package-search-paths @var{package} +These procedures are the counterpart of package record accessors +(@pxref{package Reference}). Most of them work by querying the inferior +@var{package} comes from, so the inferior must still be live when you call +these procedures. +@end deffn + +Inferior packages can be used transparently like any other package or +file-like object in G-expressions (@pxref{G-Expressions}). They are also +transparently handled by the @code{packages->manifest} procedure, which is +commonly use in manifests (@pxref{Invoking guix package, the +@option{--manifest} option of @command{guix package}}). Thus you can insert +an inferior package pretty much anywhere you would insert a regular package: +in manifests, in the @code{packages} field of your @code{operating-system} +declaration, and so on. @node Invoking guix describe @section Invoking @command{guix describe} |