guix repl command gives you access to a warm and friendly
read-eval-print loop (REPL) (see Invocación de guix repl). If you’re
getting into Guix programming—defining your own packages, writing
manifests, defining services for Guix System or Guix Home, etc.—you will
surely find it convenient to toy with ideas at the REPL.
If you use Emacs, the most convenient way to do that is with Geiser
(see La configuración perfecta), but you do not have to use Emacs to enjoy the
REPL. When using
guix repl or
guile in the terminal,
we recommend using Readline for completion and Colorized to get colorful
output. To do that, you can run:
guix install guile guile-readline guile-colorized
... and then create a .guile file in your home directory containing this:
The REPL lets you evaluate Scheme code; you type a Scheme expression at the prompt, and the REPL prints what it evaluates to:
$ guix repl scheme@(guix-user)> (+ 2 3) $1 = 5 scheme@(guix-user)> (string-append "a" "b") $2 = "ab"
It becomes interesting when you start fiddling with Guix at the REPL. The
first thing you’ll want to do is to “import” the
which gives access to the main part of the programming interface, and
perhaps a bunch of useful Guix modules. You could type
(guix)), which is valid Scheme code to import a module (see Using Guile Modules in GNU Guile Reference Manual), but the REPL provides the
use command as a shorthand notation (see REPL Commands in GNU Guile Reference Manual):
scheme@(guix-user)> ,use (guix) scheme@(guix-user)> ,use (gnu packages base)
Notice that REPL commands are introduced by a leading comma. A REPL command
use is not valid Scheme code; it’s interpreted specially by the
Guix extends the Guile REPL with additional commands for convenience. Among
build command comes in handy: it ensures that the given
file-like object is built, building it if needed, and returns its output
file name(s). In the example below, we build the
grep packages, as well as a “computed file” (see
computed-file), and we use the
scandir procedure to list the
files in Grep’s
scheme@(guix-user)> ,build coreutils $1 = "/gnu/store/…-coreutils-8.32-debug" $2 = "/gnu/store/…-coreutils-8.32" scheme@(guix-user)> ,build grep $3 = "/gnu/store/…-grep-3.6" scheme@(guix-user)> ,build (computed-file "x" #~(mkdir #$output)) building /gnu/store/…-x.drv... $4 = "/gnu/store/…-x" scheme@(guix-user)> ,use(ice-9 ftw) scheme@(guix-user)> (scandir (string-append $3 "/bin")) $5 = ("." ".." "egrep" "fgrep" "grep")
At a lower-level, a useful command is
lower: it takes a file-like
object and “lowers” it into a derivation (see Derivaciones) or a store
scheme@(guix-user)> ,lower grep $6 = #<derivation /gnu/store/…-grep-3.6.drv => /gnu/store/…-grep-3.6 7f0e639115f0> scheme@(guix-user)> ,lower (plain-file "x" "Hello!") $7 = "/gnu/store/…-x"
The full list of REPL commands can be seen by typing
,help guix and
is given below for reference.
Lower object and build it if it’s not already built, returning its output file name(s).
Lower object into a derivation or store file name and return it.
Change build verbosity to level.
This is similar to the --verbosity command-line option (see Opciones comunes de construcción): level 0 means total silence, level 1 shows build events only, and higher levels print build logs.
Run exp, a monadic expresssion, through the store monad. See La mónada del almacén, for more information.
Enter a new REPL to evaluate monadic expressions (see La mónada del almacén).
You can quit this “inner” REPL by typing