From 920fab2b8303ccae43064fdf42c4b658bb5b0c15 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Pant=C5=AF=C4=8Dek?=
 <dominik.pantucek@trustica.cz>
Date: Sun, 9 Apr 2023 19:26:52 +0200
Subject: [PATCH] Implement ldict-empty? predicate.

---
 doc/utils.md      |  6 ++++++
 src/util-dict.scm | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/doc/utils.md b/doc/utils.md
index 65bf4af..5e933ad 100644
--- a/doc/utils.md
+++ b/doc/utils.md
@@ -49,6 +49,12 @@ populating it with initial data.
 If only one argument is given, the procedure checks whether it is a
 list of equality procedure and acts accordingly.
 
+    (ldict-empty? d)
+
+* ```d``` - a ldict instance
+
+Returns true if given dictionary contains no keys.
+
 ### IO
 
     (import util-io)
diff --git a/src/util-dict.scm b/src/util-dict.scm
index 9dbf947..a904036 100644
--- a/src/util-dict.scm
+++ b/src/util-dict.scm
@@ -31,6 +31,8 @@
   TAG-LDICT
   
   make-ldict
+
+  ldict-empty?
   
   ldict-has-key?
   ldict-ref
@@ -71,6 +73,15 @@
 	   (loop (ldict-set ld (caar pairs) (cdar pairs))
 		 (cdr pairs))))))
 
+ ;; Convenience accessors
+ (define ldict-meta cadr)
+ (define ldict-equality? caadr)
+ (define ldict-list cddr)
+
+ ;; Returns true if given dictionary contains no keys
+ (define (ldict-empty? d)
+   (null? (ldict-list d)))
+
  ;; Checks whether given dictionary d contains the key k.
  (define (dict-has-key? d k)
    (if (assq k d) #t #f))