monad-repl: Add "build", "lower", and "verbosity" commands.

Fixes <https://issues.guix.gnu.org/56114>.
Reported by Maxime Devos <maximedevos@telenet.be>.

* guix/monad-repl.scm (%build-verbosity): New variable.
(evaluate/print-with-store): New procedure.
(run-in-store): Rewrite in terms of 'evaluate/print-with-store'.
(verbosity, lower, build): New meta-commands.
* doc/guix.texi (Using Guix Interactively): New node.
(The Store Monad): Link to it.
(Invoking guix repl): Likewise.
* doc/contributing.texi (Running Guix Before It Is Installed): Refer to
it.
(The Perfect Setup): Suggest 'guix install' rather than 'guix package -i'.
This commit is contained in:
Ludovic Courtès 2022-07-15 17:27:08 +02:00
parent 30915a7419
commit 4ce7f1fb24
No known key found for this signature in database
GPG key ID: 090B11993D9AEBB5
3 changed files with 192 additions and 14 deletions

View file

@ -225,8 +225,7 @@ $ ./pre-inst-env guile -c '(use-modules (guix utils)) (pk (%current-system))'
@noindent
@cindex REPL
@cindex read-eval-print loop
@dots{} and for a REPL (@pxref{Using Guile Interactively,,, guile, Guile
Reference Manual}):
@dots{} and for a REPL (@pxref{Using Guix Interactively}):
@example
$ ./pre-inst-env guile
@ -292,7 +291,7 @@ Manual}). First, you need more than an editor, you need
wonderful @url{https://nongnu.org/geiser/, Geiser}. To set that up, run:
@example
guix package -i emacs guile emacs-geiser emacs-geiser-guile
guix install emacs guile emacs-geiser emacs-geiser-guile
@end example
Geiser allows for interactive and incremental development from within

View file

@ -299,6 +299,7 @@ Programming Interface
* The Store Monad:: Purely functional interface to the store.
* G-Expressions:: Manipulating build expressions.
* Invoking guix repl:: Programming Guix in Guile.
* Using Guix Interactively:: Fine-grain interaction at the REPL.
Defining Packages
@ -7100,6 +7101,7 @@ package definitions.
* The Store Monad:: Purely functional interface to the store.
* G-Expressions:: Manipulating build expressions.
* Invoking guix repl:: Programming Guix in Guile
* Using Guix Interactively:: Fine-grain interaction at the REPL.
@end menu
@node Package Modules
@ -10860,8 +10862,9 @@ So, to exit the monad and get the desired effect, one must use
@end lisp
Note that the @code{(guix monad-repl)} module extends the Guile REPL with
new ``meta-commands'' to make it easier to deal with monadic procedures:
@code{run-in-store}, and @code{enter-store-monad}. The former is used
new ``commands'' to make it easier to deal with monadic procedures:
@code{run-in-store}, and @code{enter-store-monad} (@pxref{Using Guix
Interactively}). The former is used
to ``run'' a single monadic value through the store:
@example
@ -10886,6 +10889,9 @@ scheme@@(guile-user)>
Note that non-monadic values cannot be returned in the
@code{store-monad} REPL.
Other meta-commands are available at the REPL, such as @code{,build} to
build a file-like object (@pxref{Using Guix Interactively}).
The main syntactic forms to deal with monads in general are provided by
the @code{(guix monads)} module and are described below.
@ -11778,7 +11784,8 @@ lines at the top of the script:
@code{!#}
@end example
Without a file name argument, a Guile REPL is started:
Without a file name argument, a Guile REPL is started, allowing for
interactive use (@pxref{Using Guix Interactively}):
@example
$ guix repl
@ -11834,6 +11841,130 @@ Inhibit loading of the @file{~/.guile} file. By default, that
configuration file is loaded when spawning a @code{guile} REPL.
@end table
@node Using Guix Interactively
@section Using Guix Interactively
The @command{guix repl} command gives you access to a warm and friendly
@dfn{read-eval-print loop} (REPL) (@pxref{Invoking 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
(@pxref{The Perfect Setup}), but you do not have to use Emacs to enjoy
the REPL@. When using @command{guix repl} or @command{guile} in the
terminal, we recommend using Readline for completion and Colorized to
get colorful output. To do that, you can run:
@example
guix install guile guile-readline guile-colorized
@end example
@noindent
... and then create a @file{.guile} in your home directory containing
this:
@lisp
(use-modules (ice-9 readline) (ice-9 colorized))
(activate-readline)
(activate-colorized)
@end lisp
The REPL lets you evaluate Scheme code; you type a Scheme expression at
the prompt, and the REPL prints what it evaluates to:
@example
$ guix repl
scheme@@(guix-user)> (+ 2 3)
$1 = 5
scheme@@(guix-user)> (string-append "a" "b")
$2 = "ab"
@end example
It becomes interesting when you start fiddling with Guix at the REPL.
The first thing you'll want to do is to ``import'' the @code{(guix)}
module, which gives access to the main part of the programming
interface, and perhaps a bunch of useful Guix modules. You could type
@code{(use-modules (guix))}, which is valid Scheme code to import a
module (@pxref{Using Guile Modules,,, guile, GNU Guile Reference
Manual}), but the REPL provides the @code{use} @dfn{command} as a
shorthand notation (@pxref{REPL Commands,,, guile, GNU Guile Reference
Manual}):
@example
scheme@@(guix-user)> ,use (guix)
scheme@@(guix-user)> ,use (gnu packages base)
@end example
Notice that REPL commands are introduced by a leading comma. A REPL
command like @code{use} is not valid Scheme code; it's interpreted
specially by the REPL.
Guix extends the Guile REPL with additional commands for convenience.
Among those, the @code{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
@code{coreutils} and @code{grep} packages, as well as a ``computed
file'' (@pxref{G-Expressions, @code{computed-file}}), and we use the
@code{scandir} procedure to list the files in Grep's @code{/bin}
directory:
@example
scheme@@(guix-user)> ,build coreutils
$1 = "/gnu/store/@dots{}-coreutils-8.32-debug"
$2 = "/gnu/store/@dots{}-coreutils-8.32"
scheme@@(guix-user)> ,build grep
$3 = "/gnu/store/@dots{}-grep-3.6"
scheme@@(guix-user)> ,build (computed-file "x" #~(mkdir #$output))
building /gnu/store/@dots{}-x.drv...
$4 = "/gnu/store/@dots{}-x"
scheme@@(guix-user)> ,use(ice-9 ftw)
scheme@@(guix-user)> (scandir (string-append $3 "/bin"))
$5 = ("." ".." "egrep" "fgrep" "grep")
@end example
At a lower-level, a useful command is @code{lower}: it takes a file-like
object and ``lowers'' it into a derivation (@pxref{Derivations}) or a
store file:
@example
scheme@@(guix-user)> ,lower grep
$6 = #<derivation /gnu/store/@dots{}-grep-3.6.drv => /gnu/store/@dots{}-grep-3.6 7f0e639115f0>
scheme@@(guix-user)> ,lower (plain-file "x" "Hello!")
$7 = "/gnu/store/@dots{}-x"
@end example
The full list of REPL commands can be seen by typing @code{,help guix}
and is given below for reference.
@deffn {REPL command} build @var{object}
Lower @var{object} and build it if it's not already built, returning its
output file name(s).
@end deffn
@deffn {REPL command} lower @var{object}
Lower @var{object} into a derivation or store file name and return it.
@end deffn
@deffn {REPL command} verbosity @var{level}
Change build verbosity to @var{level}.
This is similar to the @option{--verbosity} command-line option
(@pxref{Common Build Options}): level 0 means total silence, level 1
shows build events only, and higher levels print build logs.
@end deffn
@deffn {REPL command} run-in-store @var{exp}
Run @var{exp}, a monadic expresssion, through the store monad.
@xref{The Store Monad}, for more information.
@end deffn
@deffn {REPL command} enter-store-monad
Enter a new REPL to evaluate monadic expressions (@pxref{The Store
Monad}). You can quit this ``inner'' REPL by typing @code{,q}.
@end deffn
@c *********************************************************************
@node Utilities
@chapter Utilities

View file

@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2014, 2015, 2016, 2022 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@ -21,6 +21,12 @@ (define-module (guix monad-repl)
#:use-module (guix monads)
#:use-module (guix utils)
#:use-module (guix packages)
#:use-module (guix status)
#:autoload (guix gexp) (lower-object)
#:use-module ((guix derivations)
#:select (derivation?
derivation->output-paths built-derivations))
#:use-module (ice-9 match)
#:use-module (ice-9 pretty-print)
#:use-module (system repl repl)
#:use-module (system repl common)
@ -69,16 +75,58 @@ (define (store-monad-language store)
#:guile-for-build guile)
'store-monad)))
(define %build-verbosity
;; Current build verbosity level.
1)
(define* (evaluate/print-with-store mvalue #:key build?)
"Run monadic value MVALUE in the store monad and print its value."
(with-store store
(set-build-options store
#:print-build-trace #t
#:print-extended-build-trace? #t
#:multiplexed-build-output? #t)
(with-status-verbosity %build-verbosity
(let* ((guile (or (%guile-for-build)
(default-guile-derivation store)))
(values (run-with-store store
(if build?
(mlet %store-monad ((obj mvalue))
(if (derivation? obj)
(mbegin %store-monad
(built-derivations (list obj))
(return
(match (derivation->output-paths obj)
(((_ . files) ...) files))))
(return (list obj))))
(mlet %store-monad ((obj mvalue))
(return (list obj))))
#:guile-for-build guile)))
(for-each (lambda (value)
(run-hook before-print-hook value)
(pretty-print value))
values)))))
(define-meta-command ((run-in-store guix) repl (form))
"run-in-store EXP
Run EXP through the store monad."
(with-store store
(let* ((guile (or (%guile-for-build)
(default-guile-derivation store)))
(value (run-with-store store (repl-eval repl form)
#:guile-for-build guile)))
(run-hook before-print-hook value)
(pretty-print value))))
(evaluate/print-with-store (repl-eval repl form)))
(define-meta-command ((verbosity guix) repl (level))
"verbosity LEVEL
Change build verbosity to LEVEL."
(set! %build-verbosity (repl-eval repl level)))
(define-meta-command ((lower guix) repl (form))
"lower OBJECT
Lower OBJECT into a derivation or store file and return it."
(evaluate/print-with-store (lower-object (repl-eval repl form))))
(define-meta-command ((build guix) repl (form))
"build OBJECT
Lower OBJECT and build it, returning its output file name(s)."
(evaluate/print-with-store (lower-object (repl-eval repl form))
#:build? #t))
(define-meta-command ((enter-store-monad guix) repl)
"enter-store-monad