GNU bug report logs - #78277
[PATCH] ui: Allow evaluating multi-expressions strings with read/eval.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: guix-patches <at> gnu.org
Cc: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Subject: [PATCH] ui: Allow evaluating multi-expressions strings with read/eval.
Date: Tue,  6 May 2025 16:42:23 +0900

This can be useful when evaluating a scheme->file store output for example,
which has multiple top level expressions.

* guix/ui.scm (read/eval): Also accept a port object as argument.  Read and
evaluate all expressions from input port or string.

Change-Id: I0213706fa4824c3a8ffe5d93f44f263048cb62c2
---
 guix/ui.scm | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/guix/ui.scm b/guix/ui.scm
index d462f7133e0..cd9eb1013d0 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -15,7 +15,7 @@
 ;;; Copyright © 2019, 2020 Tobias Geerinckx-Rice <me <at> tobias.gr>
 ;;; Copyright © 2019, 2021 Simon Tournier <zimon.toutoune <at> gmail.com>
 ;;; Copyright © 2020 Arun Isaac <arunisaac <at> systemreboot.net>
-;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
+;;; Copyright © 2020, 2025 Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
 ;;; Copyright © 2018 Steve Sprang <scs <at> stevesprang.com>
 ;;; Copyright © 2022 Taiju HIGASHI <higashi <at> taiju.info>
 ;;; Copyright © 2022 Liliana Marie Prikler <liliana.prikler <at> gmail.com>
@@ -926,13 +926,18 @@ (define %guix-user-module
       module)))
 
 (define (read/eval str)
-  "Read and evaluate STR, raising an error if something goes wrong."
-  (let ((exp (catch #t
-               (lambda ()
-                 (call-with-input-string str read))
-               (lambda args
-                 (leave (G_ "failed to read expression ~s: ~s~%")
-                        str args)))))
+  "Read and evaluate STR, which can also be a port, raising an error if
+something goes wrong.  STR may contain one or more expressions; the return
+value is that of the last evaluated expression."
+  (define (read/safe port)
+    (catch #t
+      (lambda ()
+        (read port))
+      (lambda args
+        (leave (G_ "failed to read expression ~s: ~s~%")
+               str args))))
+
+  (define (eval/safe exp)
     (catch #t
       (lambda ()
         (eval exp (force %guix-user-module)))
@@ -956,7 +961,19 @@ (define (read/eval str)
           ((error args ...)
            (apply display-error #f (current-error-port) args))
           (what? #f))
-        (exit 1)))))
+        (exit 1))))
+
+  (let ((call-with-port-or-string (if (port? str)
+                                      call-with-port
+                                      call-with-input-string)))
+    (call-with-port-or-string
+     str
+     (lambda (port)
+       (let loop ((exp (read/safe port))
+                  (result #f))
+         (if (eof-object? exp)
+             result
+             (loop (read/safe port) (eval/safe exp))))))))
 
 (define (read/eval-package-expression str)
   "Read and evaluate STR and return the package it refers to, or exit an

base-commit: a897159a7cdb521d64fd2a5034b6c895968a7f51
-- 
2.49.0

Message #8 received at 78277 <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 78277 <at> debbugs.gnu.org, Josselin Poiret <dev <at> jpoiret.xyz>,
 Simon Tournier <zimon.toutoune <at> gmail.com>, Mathieu Othacehe <othacehe <at> gnu.org>,
 Tobias Geerinckx-Rice <me <at> tobias.gr>, Christopher Baines <guix <at> cbaines.net>
Subject: Re: [bug#78277] [PATCH] ui: Allow evaluating multi-expressions
 strings with read/eval.
Date: Wed, 07 May 2025 17:27:50 +0200

Hi,

Maxim Cournoyer <maxim.cournoyer <at> gmail.com> writes:

> This can be useful when evaluating a scheme->file store output for example,
> which has multiple top level expressions.
>
> * guix/ui.scm (read/eval): Also accept a port object as argument.  Read and
> evaluate all expressions from input port or string.
>
> Change-Id: I0213706fa4824c3a8ffe5d93f44f263048cb62c2

Very useful, thanks!

Perhaps you can add a test for example with ‘guix build -e’ in
‘tests/guix-build.sh’?

Otherwise, LGTM.

Ludo’.

Message #13 received at 78277-done <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: Josselin Poiret <dev <at> jpoiret.xyz>,
 Simon Tournier <zimon.toutoune <at> gmail.com>, Mathieu Othacehe <othacehe <at> gnu.org>,
 Tobias Geerinckx-Rice <me <at> tobias.gr>, 78277-done <at> debbugs.gnu.org,
 Christopher Baines <guix <at> cbaines.net>
Subject: Re: [bug#78277] [PATCH] ui: Allow evaluating multi-expressions
 strings with read/eval.
Date: Fri, 09 May 2025 23:09:01 +0900

Hi!

Ludovic Courtès <ludo <at> gnu.org> writes:

> Hi,
>
> Maxim Cournoyer <maxim.cournoyer <at> gmail.com> writes:
>
>> This can be useful when evaluating a scheme->file store output for example,
>> which has multiple top level expressions.
>>
>> * guix/ui.scm (read/eval): Also accept a port object as argument.  Read and
>> evaluate all expressions from input port or string.
>>
>> Change-Id: I0213706fa4824c3a8ffe5d93f44f263048cb62c2
>
> Very useful, thanks!
>
> Perhaps you can add a test for example with ‘guix build -e’ in
> ‘tests/guix-build.sh’?

Done!  See commit 18ed22536d0.  Thanks for the review!

-- 
Maxim

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