diff -Nru lua-readline-3.0/debian/changelog lua-readline-3.1/debian/changelog
--- lua-readline-3.0/debian/changelog	2021-08-17 08:14:38.000000000 +0000
+++ lua-readline-3.1/debian/changelog	2022-04-30 04:46:29.000000000 +0000
@@ -1,3 +1,9 @@
+lua-readline (3.1-1) unstable; urgency=medium
+
+  * New upstream release.
+
+ -- Sergei Golovan <sgolovan@debian.org>  Sat, 30 Apr 2022 07:46:29 +0300
+
 lua-readline (3.0-1) unstable; urgency=medium
 
   * New upstream release.
diff -Nru lua-readline-3.0/doc/readline.html lua-readline-3.1/doc/readline.html
--- lua-readline-3.0/doc/readline.html	2021-04-18 05:42:54.000000000 +0000
+++ lua-readline-3.1/doc/readline.html	2022-04-20 04:21:45.000000000 +0000
@@ -152,7 +152,7 @@
 <A HREF="#custom">Custom Completion</A>
 is now provided.
 </P><P>
-This module does not work <CODE>lua -i</CODE>
+This module does not work with <CODE>lua -i</CODE>
 because that runs its own <I>readline</I>,
 and the two conflict with each other.
 </P>
@@ -385,8 +385,7 @@
 then you need to find the appropriate directory with:<BR><CODE>
  &nbsp; find /usr/lib -name 'libreadline.*' -print</CODE><BR>
 and then invoke:<BR><CODE>
- &nbsp; luarocks install \<BR>
- &nbsp; https://www.pjb.com.au/comp/lua/readline-3.0-0.rockspec \<BR>
+ &nbsp; luarocks install readline\<BR>
  &nbsp; READLINE_INCDIR=/usr/local/Cellar/readline/8.1/include \<BR>
  &nbsp; READLINE_LIBDIR=/usr/local/Cellar/readline/8.1/lib \<BR>
  &nbsp; HISTORY_INCDIR=/usr/local/Cellar/readline/8.1/include \<BR>
diff -Nru lua-readline-3.0/readline.lua lua-readline-3.1/readline.lua
--- lua-readline-3.0/readline.lua	2021-04-18 05:42:54.000000000 +0000
+++ lua-readline-3.1/readline.lua	2022-04-20 04:21:45.000000000 +0000
@@ -141,6 +141,7 @@
 				Option[k] = v
 				prv.clear_history()
 				local rc = M.read_history( Option['histfile'] )  -- 1.2
+				OldHistoryLength = prv.history_length()  -- 3.1
 			end
 		elseif k == 'keeplines' or k == 'minlength' then
 			if type(v) ~= 'number' then
@@ -204,10 +205,47 @@
 		if rc ~= 0 then warn('append_history: '..prv.strerror(rc)) end
 		rc = prv.history_truncate_file ( histfile, Option['keeplines'] )
 		if rc ~= 0 then warn('history_truncate_file: '..prv.strerror(rc)) end
+		-- reset OldHistoryLength in case it's used again ... er: 3.1?
+		-- OldHistoryLength = n   -- is this useful ?
 	end
 	return
 end
 
+--[[
+20220420
+https://tiswww.cwru.edu/php/chet/readline/history.html#SEC15
+
+Function: int read_history (const char *filename)
+    Add the contents of filename to the history list, a line at a 
+    time. If filename is NULL, then read from `~/.history'. Returns 0
+    if successful, or errno if not.
+
+Function: int read_history_range (const char *filename, int from, int to)
+    Read a range of lines from filename, adding them to the history 
+    list. Start reading at line from and end at to. If from is zero, start
+    at the beginning. If to is less than from, then read until the end of
+    the file. If filename is NULL, then read from `~/.history'. Returns 
+    0 if successful, or errno if not.
+
+Function: int write_history (const char *filename)
+    Write the current history to filename, overwriting filename if 
+    necessary. If filename is NULL, then write the history list to
+    `~/.history'. Returns 0 on success, or errno on a read or write error.
+
+Function: int append_history (int nelements, const char *filename)
+    Append the last nelements of the history list to filename. If filename 
+    is NULL, then append to `~/.history'. Returns 0 on success, or errno
+    on a read or write error.
+
+Function: int history_truncate_file (const char *filename, int nlines)
+    Truncate the history file filename, leaving only the last nlines 
+    lines. If filename is NULL, then `~/.history' is truncated. Returns
+    0 on success, or errno on failure.
+
+Seems something's going wrong with n-OldHistoryLength ...
+]]
+
+
 function M.strerror ( errnum )
 	return prv.strerror(tonumber(errnum))
 end