Add (guix inferior) and (guix scripts repl).

* guix/inferior.scm, guix/scripts/repl.scm, tests/inferior.scm: New
files.
* Makefile.am (MODULES): Add 'guix/scripts/repl.scm' and
'guix/inferior.scm'.
(SCM_TESTS): Add 'tests/inferior.scm'.
* doc/guix.texi (Invoking guix repl): New node.

1 files changed, 199 insertions, 0 deletions

diff --git a/guix/scripts/repl.scm b/guix/scripts/repl.scm
new file mode 100644
index 0000000000..b157833a49
--- /dev/null
+++ b/guix/scripts/repl.scm
@@ -0,0 +1,199 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; 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/>.
+
+(define-module (guix scripts repl)
+  #:use-module (guix ui)
+  #:use-module (guix scripts)
+  #:use-module (guix utils)
+  #:use-module (guix packages)
+  #:use-module (gnu packages)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-37)
+  #:use-module (ice-9 match)
+  #:use-module (rnrs bytevectors)
+  #:autoload   (system repl repl) (start-repl)
+  #:autoload   (system repl server)
+                  (make-tcp-server-socket make-unix-domain-server-socket)
+  #:export (machine-repl
+            guix-repl))
+
+;;; Commentary:
+;;;
+;;; This command provides a Guile REPL
+
+(define %default-options
+  `((type . guile)))
+
+(define %options
+  (list (option '(#\h "help") #f #f
+                (lambda args
+                  (show-help)
+                  (exit 0)))
+        (option '(#\V "version") #f #f
+                (lambda args
+                  (show-version-and-exit "guix repl")))
+        (option '(#\t "type") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'type (string->symbol arg) result)))
+        (option '("listen") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'listen arg result)))))
+
+
+(define (show-help)
+  (display (G_ "Usage: guix repl [OPTIONS...]
+Start a Guile REPL in the Guix execution environment.\n"))
+  (display (G_ "
+  -t, --type=TYPE        start a REPL of the given TYPE"))
+  (newline)
+  (display (G_ "
+  -h, --help             display this help and exit"))
+  (display (G_ "
+  -V, --version          display version information and exit"))
+  (newline)
+  (show-bug-report-information))
+
+(define (self-quoting? x)
+  "Return #t if X is self-quoting."
+  (letrec-syntax ((one-of (syntax-rules ()
+                            ((_) #f)
+                            ((_ pred rest ...)
+                             (or (pred x)
+                                 (one-of rest ...))))))
+    (one-of symbol? string? pair? null? vector?
+            bytevector? number? boolean?)))
+
+(define user-module
+  ;; Module where we execute user code.
+  (let ((module (resolve-module '(guix-user) #f #f #:ensure #t)))
+    (beautify-user-module! module)
+    module))
+
+(define* (machine-repl #:optional
+                       (input (current-input-port))
+                       (output (current-output-port)))
+  "Run a machine-usable REPL over ports INPUT and OUTPUT.
+
+The protocol of this REPL is meant to be machine-readable and provides proper
+support to represent multiple-value returns, exceptions, objects that lack a
+read syntax, and so on.  As such it is more convenient and robust than parsing
+Guile's REPL prompt."
+  (define (value->sexp value)
+    (if (self-quoting? value)
+        `(value ,value)
+        `(non-self-quoting ,(object-address value)
+                           ,(object->string value))))
+
+  (write `(repl-version 0 0) output)
+  (newline output)
+  (force-output output)
+
+  (let loop ()
+    (match (read input)
+      ((? eof-object?) #t)
+      (exp
+       (catch #t
+         (lambda ()
+           (let ((results (call-with-values
+                              (lambda ()
+
+                                (primitive-eval exp))
+                            list)))
+             (write `(values ,@(map value->sexp results))
+                    output)
+             (newline output)
+             (force-output output)))
+         (lambda (key . args)
+           (write `(exception ,key ,@(map value->sexp args)))
+           (newline output)
+           (force-output output)))
+       (loop)))))
+
+(define (call-with-connection spec thunk)
+  "Dynamically-bind the current input and output ports according to SPEC and
+call THUNK."
+  (if (not spec)
+      (thunk)
+
+      ;; Note: the "PROTO:" prefix in SPEC is here so that we can eventually
+      ;; parse things like "fd:123" in a non-ambiguous way.
+      (match (string-index spec #\:)
+        (#f
+         (leave (G_ "~A: invalid listen specification~%") spec))
+        (index
+         (let ((protocol (string-take spec index))
+               (address  (string-drop spec (+ index 1))))
+           (define socket
+             (match protocol
+               ("tcp"
+                (make-tcp-server-socket #:port (string->number address)))
+               ("unix"
+                (make-unix-domain-server-socket #:path address))
+               (_
+                (leave (G_ "~A: unsupported protocol family~%")
+                       protocol))))
+
+           (listen socket 10)
+           (let loop ()
+             (match (accept socket)
+               ((connection . address)
+                (if (= AF_UNIX (sockaddr:fam address))
+                    (info (G_ "accepted connection~%"))
+                    (info (G_ "accepted connection from ~a~%")
+                          (inet-ntop (sockaddr:fam address)
+                                     (sockaddr:addr address))))
+                (dynamic-wind
+                  (const #t)
+                  (lambda ()
+                    (parameterize ((current-input-port connection)
+                                   (current-output-port connection))
+                      (thunk)))
+                  (lambda ()
+                    (false-if-exception (close-port connection))
+                    (info (G_ "connection closed~%"))))))
+             (loop)))))))
+
+
+(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))
+                %default-options))
+
+  (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)
+                (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)
+;; End: