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authorLudovic Courtès <ludo@gnu.org>2019-06-10 17:09:35 +0200
committerLudovic Courtès <ludo@gnu.org>2019-07-04 18:05:02 +0200
commit92a4087bf4862d5ba9b77111eba3c68c2a1c4679 (patch)
tree1f8c7965dc1a4b11cecd2f6aa37bc8c022ea6f4a /guix/repl.scm
parent2ca41030d5189d83ea2a28ea64cf0e19efed5fd7 (diff)
Add (guix repl).
* guix/scripts/repl.scm: Use (guix repl). (self-quoting?, machine-repl): Remove. * guix/repl.scm: New file. * Makefile.am (MODULES): Add it.
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+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018, 2019 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 repl)
+ #:use-module (rnrs bytevectors)
+ #:use-module (ice-9 match)
+ #:export (send-repl-response
+ machine-repl))
+
+;;; Commentary:
+;;;
+;;; This module implements the "machine-readable" REPL provided by
+;;; 'guix repl -t machine'. It's a lightweight module meant to be
+;;; embedded in any Guile process providing REPL functionality.
+;;;
+;;; Code:
+
+(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 (send-repl-response exp output)
+ "Write the response corresponding to the evaluation of EXP to PORT, an
+output port."
+ (define (value->sexp value)
+ (if (self-quoting? value)
+ `(value ,value)
+ `(non-self-quoting ,(object-address value)
+ ,(object->string value))))
+
+ (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))))
+
+(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."
+ (write `(repl-version 0 0) output)
+ (newline output)
+ (force-output output)
+
+ (let loop ()
+ (match (read input)
+ ((? eof-object?) #t)
+ (exp
+ (send-repl-response exp output)
+ (loop)))))