From a94469c651ae096b84c9b6389b8278113da00100 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Tue, 7 Dec 2010 20:43:49 +0100
Subject: [PATCH] Add a record type printer for vlists/vhashes.

* module/ice-9/vlist.scm (<vlist>): Add a record type printer.
---
 module/ice-9/vlist.scm | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/module/ice-9/vlist.scm b/module/ice-9/vlist.scm
index d72e6c108..5ea09362c 100644
--- a/module/ice-9/vlist.scm
+++ b/module/ice-9/vlist.scm
@@ -19,6 +19,7 @@
 (define-module (ice-9 vlist)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-9 gnu)
   #:use-module (srfi srfi-26)
 
   #:export (vlist? vlist-cons vlist-head vlist-tail vlist-null?
@@ -148,6 +149,21 @@
   (base    vlist-base)
   (offset  vlist-offset))
 
+(set-record-type-printer! <vlist>
+                          (lambda (vl port)
+                            (cond ((vlist-null? vl)
+                                   (format port "#<vlist ()>"))
+                                  ((block-hash-table (vlist-base vl))
+                                   (format port "#<vhash ~x ~a pairs>"
+                                           (object-address vl)
+                                           (vhash-fold (lambda (k v r)
+                                                         (+ 1 r))
+                                                       0
+                                                       vl)))
+                                  (else
+                                   (format port "#<vlist ~a>"
+                                           (vlist->list vl))))))
+
 
 (define vlist-null
   ;; The empty vlist.
-- 
2.20.1