guix repl: Add script execution.

* guix/scripts/repl.scm: Add filename options for script execution.
* doc/guix.texi (Invoking guix repl): Document it.
* tests/guix-repl.sh: Test it.
* Makefile.am: (SH_TESTS): Add it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

4 files changed, 179 insertions, 34 deletions

diff --git a/Makefile.am b/Makefile.am
index 9cf9318e8a..8988cdfa12 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -477,6 +477,7 @@ SH_TESTS =					\
   tests/guix-environment-container.sh		\
   tests/guix-graph.sh				\
   tests/guix-describe.sh			\
+  tests/guix-repl.sh     			\
   tests/guix-lint.sh
 
 TESTS = $(SCM_TESTS) $(SH_TESTS)
diff --git a/doc/guix.texi b/doc/guix.texi
index 510347b222..d55eaff02c 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -239,7 +239,7 @@ Programming Interface
 * Derivations::                 Low-level interface to package derivations.
 * The Store Monad::             Purely functional interface to the store.
 * G-Expressions::               Manipulating build expressions.
-* Invoking guix repl::          Fiddling with Guix interactively.
+* Invoking guix repl::          Programming Guix in Guile
 
 Defining Packages
 
@@ -5474,7 +5474,7 @@ package definitions.
 * Derivations::                 Low-level interface to package derivations.
 * The Store Monad::             Purely functional interface to the store.
 * G-Expressions::               Manipulating build expressions.
-* Invoking guix repl::          Fiddling with Guix interactively.
+* Invoking guix repl::          Programming Guix in Guile
 @end menu
 
 @node Package Modules
@@ -8248,12 +8248,47 @@ has an associated gexp compiler, such as a @code{<package>}.
 @node Invoking guix repl
 @section Invoking @command{guix repl}
 
-@cindex REPL, read-eval-print loop
-The @command{guix repl} command spawns a Guile @dfn{read-eval-print loop}
-(REPL) for interactive programming (@pxref{Using Guile Interactively,,, guile,
-GNU Guile Reference Manual}).  Compared to just launching the @command{guile}
+@cindex REPL, read-eval-print loop, script
+The @command{guix repl} command makes it easier to program Guix in Guile
+by launching a Guile @dfn{read-eval-print loop} (REPL) for interactive
+programming (@pxref{Using Guile Interactively,,, guile,
+GNU Guile Reference Manual}), or by running Guile scripts
+(@pxref{Running Guile Scripts,,, guile,
+GNU Guile Reference Manual}).
+Compared to just launching the @command{guile}
 command, @command{guix repl} guarantees that all the Guix modules and all its
-dependencies are available in the search path.  You can use it this way:
+dependencies are available in the search path.
+
+The general syntax is:
+
+@example
+guix repl @var{options} [@var{file} @var{args}]
+@end example
+
+When a @var{file} argument is provided, @var{file} is
+executed as a Guile scripts:
+
+@example
+guix repl my-script.scm
+@end example
+
+To pass arguments to the script, use @code{--} to prevent them from
+being interpreted as arguments to @command{guix repl} itself:
+
+@example
+guix repl -- my-script.scm --input=foo.txt
+@end example
+
+To make a script executable directly from the shell, using the guix
+executable that is on the user's search path, add the following two
+lines at the top of the script:
+
+@example
+@code{#!/usr/bin/env -S guix repl --}
+@code{!#}
+@end example
+
+Without a file name argument, a Guile REPL is started:
 
 @example
 $ guix repl
@@ -8302,7 +8337,7 @@ Add @var{directory} to the front of the package module search path
 (@pxref{Package Modules}).
 
 This allows users to define their own packages and make them visible to
-the command-line tool.
+the script or REPL.
 
 @item -q
 Inhibit loading of the @file{~/.guile} file.  By default, that
diff --git a/guix/scripts/repl.scm b/guix/scripts/repl.scm
index ff1f208894..e2679f4301 100644
--- a/guix/scripts/repl.scm
+++ b/guix/scripts/repl.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2020 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2020 Konrad Hinsen <konrad.hinsen@fastmail.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,6 +23,7 @@
   #:use-module (guix scripts)
   #:use-module (guix repl)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-37)
   #:use-module (ice-9 match)
   #:use-module (rnrs bytevectors)
@@ -32,7 +34,8 @@
 
 ;;; Commentary:
 ;;;
-;;; This command provides a Guile REPL
+;;; This command provides a Guile script runner and REPL in an environment
+;;; that contains all the modules comprising Guix.
 
 (define %default-options
   `((type . guile)))
@@ -63,8 +66,9 @@
 
 
 (define (show-help)
-  (display (G_ "Usage: guix repl [OPTIONS...]
-Start a Guile REPL in the Guix execution environment.\n"))
+  (display (G_ "Usage: guix repl [OPTIONS...] [-- FILE ARGS...]
+In the Guix execution environment, run FILE as a Guile script with
+command-line arguments ARGS.  If no FILE is given, start a Guile REPL.\n"))
   (display (G_ "
   -t, --type=TYPE        start a REPL of the given TYPE"))
   (display (G_ "
@@ -135,12 +139,13 @@ call THUNK."
 
 (define (guix-repl . args)
   (define opts
-    ;; Return the list of package names.
     (args-fold* args %options
                 (lambda (opt name arg result)
                   (leave (G_ "~A: unrecognized option~%") name))
                 (lambda (arg result)
-                  (leave (G_ "~A: extraneous argument~%") arg))
+                  (append `((script . ,arg)
+                            (ignore-dot-guile . #t))
+                          result))
                 %default-options))
 
   (define user-config
@@ -148,28 +153,48 @@ call THUNK."
            (lambda (home)
              (string-append home "/.guile"))))
 
+  (define (set-user-module)
+    (set-current-module user-module)
+    (when (and (not (assoc-ref opts 'ignore-dot-guile?))
+               user-config
+               (file-exists? user-config))
+      (load user-config)))
+
+  (define script
+    (reverse
+     (filter-map (match-lambda
+                   (('script . script) script)
+                   (_ #f))
+                 opts)))
+
   (with-error-handling
-    (let ((type (assoc-ref opts 'type)))
-      (call-with-connection (assoc-ref opts 'listen)
-        (lambda ()
-          (case type
-            ((guile)
-             (save-module-excursion
-              (lambda ()
-                (set-current-module user-module)
-                (when (and (not (assoc-ref opts 'ignore-dot-guile?))
-                           user-config
-                           (file-exists? user-config))
-                  (load user-config))
-
-                ;; Do not exit repl on SIGINT.
-                ((@@ (ice-9 top-repl) call-with-sigint)
-                 (lambda ()
-                   (start-repl))))))
-            ((machine)
-             (machine-repl))
-            (else
-             (leave (G_ "~a: unknown type of REPL~%") type))))))))
+
+    (unless (null? script)
+      ;; Run script
+      (save-module-excursion
+       (lambda ()
+         (set-program-arguments script)
+         (set-user-module)
+         (load-in-vicinity "." (car script)))))
+
+    (when (null? script)
+      ;; Start REPL
+      (let ((type (assoc-ref opts 'type)))
+        (call-with-connection (assoc-ref opts 'listen)
+          (lambda ()
+            (case type
+              ((guile)
+               (save-module-excursion
+                (lambda ()
+                  (set-user-module)
+                  ;; Do not exit repl on SIGINT.
+                  ((@@ (ice-9 top-repl) call-with-sigint)
+                   (lambda ()
+                     (start-repl))))))
+              ((machine)
+               (machine-repl))
+              (else
+               (leave (G_ "~a: unknown type of REPL~%") type)))))))))
 
 ;; Local Variables:
 ;; eval: (put 'call-with-connection 'scheme-indent-function 1)
diff --git a/tests/guix-repl.sh b/tests/guix-repl.sh
new file mode 100644
index 0000000000..e1c2b8241f
--- /dev/null
+++ b/tests/guix-repl.sh
@@ -0,0 +1,84 @@
+# GNU Guix --- Functional package management for GNU
+# Copyright © 2020 Simon Tournier <zimon.toutoune@gmail.com>
+# Copyright © 2020 Konrad Hinsen <konrad.hinsen@fastmail.net>
+#
+# This file is part of GNU Guix.
+#
+# GNU Guix is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or (at
+# your option) any later version.
+#
+# GNU Guix is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+#
+# Test the `guix repl' command-line utility.
+#
+
+guix repl --version
+
+test_directory="`mktemp -d`"
+export test_directory
+trap 'chmod -Rf +w "$test_directory"; rm -rf "$test_directory"' EXIT
+
+tmpfile="$test_directory/foo.scm"
+rm -f "$tmpfile"
+trap 'rm -f "$tmpfile"' EXIT
+
+module_dir="t-guix-repl-$$"
+mkdir "$module_dir"
+trap 'rm -rf "$module_dir"' EXIT
+
+
+cat > "$tmpfile"<<EOF
+(use-modules (guix packages)
+             (gnu packages base))
+
+(format #t "~a\n" (package-name coreutils))
+EOF
+
+test "`guix repl "$tmpfile"`" = "coreutils"
+
+
+cat > "$module_dir/foo.scm"<<EOF
+(define-module (foo)
+  #:use-module (guix packages)
+  #:use-module (gnu packages base))
+
+(define-public dummy
+  (package (inherit hello)
+    (name "dummy")
+    (version "42")
+    (synopsis "dummy package")
+    (description "dummy package. Only used for testing purposes.")))
+EOF
+
+cat > "$tmpfile"<<EOF
+(use-modules (guix packages)
+             (foo))
+
+(format #t "~a\n" (package-version dummy))
+EOF
+
+test "`guix repl "$tmpfile" -L "$module_dir"`" = "42"
+
+cat > "$tmpfile"<<EOF
+(format #t "~a\n" (cdr (command-line)))
+EOF
+
+test "`guix repl -- "$tmpfile" -a b --input=foo.txt`" = "(-a b --input=foo.txt)"
+
+cat > "$tmpfile"<<EOF
+#!$(type -P env) -S guix repl --
+!#
+(format #t "~a\n" (cdr (command-line)))
+EOF
+chmod 755 $tmpfile
+
+test "`"$tmpfile" -a b --input=foo.txt`" = "(-a b --input=foo.txt)"