From 5f9d1d22af102a8e9d2a769ea02243fb5763fe74 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 19 Jul 2014 13:04:33 -0700
Subject: * hash.c (hash_construct): Nullify the pairs argument so that it
 works correctly with an empty vector.

* txr.1: Write missing documentation for hash-construct.
---
 ChangeLog |  7 +++++++
 hash.c    |  2 ++
 txr.1     | 18 ++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index f84751b4..d2a40266 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-07-19  Kaz Kylheku  <kaz@kylheku.com>
+
+	* hash.c (hash_construct): Nullify the pairs argument so that
+	it works correctly with an empty vector.
+
+	* txr.1: Write missing documentation for hash-construct.
+
 2014-07-19  Kaz Kylheku  <kaz@kylheku.com>
 
 	* eval.c (mapdov): New function.
diff --git a/hash.c b/hash.c
index f4692d56..92a05191 100644
--- a/hash.c
+++ b/hash.c
@@ -812,6 +812,8 @@ val hash_construct(val hashv_args, val pairs)
 {
   val hash = hashv(hashv_args);
 
+  pairs = nullify(pairs);
+
   for (; pairs; pairs = cdr(pairs)) {
     val pair = car(pairs);
     sethash(hash, first(pair), second(pair));
diff --git a/txr.1 b/txr.1
index 47ac3388..666d238c 100644
--- a/txr.1
+++ b/txr.1
@@ -11769,6 +11769,24 @@ the equal function instead.
 In addition to storing key-value pairs, a hash table can have a piece of
 information associated with it, called the user data.
 
+.SS Function hash-construct
+
+.TP
+Syntax:
+
+  (hash-construct <hash-args> <key-val-pairs>)
+
+.TP
+Description:
+
+The hash-construct function constructs a populated hash in one step. The <hash-args>
+argument specifies a list suitable as an argument list in a call to the hash function.
+The <key-val-pairs> is a sequence of pairs, which are two-element lists representing
+key-value pairs.
+
+A hash is constructed as if by a call to [apply hash <hash-args>], then populated
+with the specified pairs, and returned.
+
 .SS Function hash-update
 
 .TP
-- 
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