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repl: Return stack traces along with exceptions.

* guix/repl.scm (repl-prompt): New variable.
(stack->frames): New procedure.
(send-repl-response)[frame->sexp, handle-exception]: New procedure.
Pass HANDLE-EXCEPTION as a pre-unwind handler.
(machine-repl): Define 'tag'.  Bump protocol version to (0 1 1).
Wrap 'loop' call in 'call-with-prompt'.
Ludovic Courtès 1 year ago
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1 changed files with 54 additions and 10 deletions
  1. +54

+ 54
- 10
guix/repl.scm View File

@ -17,6 +17,8 @@
;;; along with GNU Guix. If not, see <>.
(define-module (guix repl)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:export (send-repl-response
@ -39,6 +41,17 @@
(one-of symbol? string? keyword? pair? null? array?
number? boolean? char?)))
(define repl-prompt
;; Current REPL prompt or #f.
(make-parameter #f))
(define (stack->frames stack)
"Return STACK's frames as a list."
(unfold (cute >= <> (stack-length stack))
(cut stack-ref stack <>)
(define* (send-repl-response exp output
#:key (version '(0 0)))
"Write the response corresponding to the evaluation of EXP to PORT, an
@ -49,6 +62,32 @@ output port. VERSION is the client's protocol version we are targeting."
`(non-self-quoting ,(object-address value)
,(object->string value))))
(define (frame->sexp frame)
`(,(frame-procedure-name frame)
,(match (frame-source frame)
((_ (? string? file) (? integer? line) . (? integer? column))
(list file line column))
'(#f #f #f)))))
(define (handle-exception key . args)
(define reply
(match version
((0 1 (? positive?) _ ...)
;; Protocol (0 1 1) and later.
(let ((stack (if (repl-prompt)
(make-stack #t handle-exception (repl-prompt))
(make-stack #t))))
`(exception (arguments ,key ,@(map value->sexp args))
(stack ,@(map frame->sexp (stack->frames stack))))))
;; Protocol (0 0).
`(exception ,key ,@(map value->sexp args)))))
(write reply output)
(newline output)
(force-output output))
(catch #t
(lambda ()
(let ((results (call-with-values
@ -59,10 +98,8 @@ output port. VERSION is the client's protocol version we are targeting."
(newline output)
(force-output output)))
(lambda (key . args)
(write `(exception ,key ,@(map value->sexp args)))
(newline output)
(force-output output))))
(const #t)
(define* (machine-repl #:optional
(input (current-input-port))
@ -73,6 +110,9 @@ 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 tag
(make-prompt-tag "repl-prompt"))
(define (loop exp version)
(match exp
((? eof-object?) #t)
@ -81,7 +121,7 @@ Guile's REPL prompt."
#:version version)
(loop (read input) version))))
(write `(repl-version 0 1) output)
(write `(repl-version 0 1 1) output)
(newline output)
(force-output output)
@ -91,8 +131,12 @@ Guile's REPL prompt."
;; 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))
(loop exp '(0 0)))))
(call-with-prompt tag
(lambda ()
(parameterize ((repl-prompt tag))
(match (read input)
((() 'repl-version version ...)
(loop (read input) version))
(loop exp '(0 0))))))
(const #f)))