@@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -39,9 +39,10 @@
(one-of symbol? string? keyword? pair? null? array?
number? boolean? char?)))
-(define (send-repl-response exp output)
+(define* (send-repl-response exp output
+ #:key (version '(0 0)))
"Write the response corresponding to the evaluation of EXP to PORT, an
-output port."
+output port. VERSION is the client's protocol version we are targeting."
(define (value->sexp value)
(if (self-quoting? value)
`(value ,value)
@@ -72,13 +73,26 @@ 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)
+ (define (loop exp version)
+ (match exp
((? eof-object?) #t)
(exp
- (send-repl-response exp output)
- (loop)))))
+ (send-repl-response exp output
+ #:version version)
+ (loop (read input) version))))
+
+ (write `(repl-version 0 1) output)
+ (newline output)
+ (force-output output)
+
+ ;; In protocol version (0 0), clients would not send their supported
+ ;; protocol version. Thus, the code below checks for two case: (1) a (0 0)
+ ;; client that directly sends an expression to evaluate, and (2) a more
+ ;; recent client that sends (() repl-version ...). This form is chosen to
+ ;; be unambiguously distinguishable from a regular Scheme expression.
+
+ (match (read input)
+ ((() 'repl-version version ...)
+ (loop (read input) version))
+ (exp
+ (loop exp '(0 0)))))