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A binding for the GNU readline library.


[procedure] (gnu-readline PROMPT)

Reads a line using the GNU readline() function and returns a string. PROMPT should also be a string.

[procedure] (gnu-readline-clear-history)

Clears the history buffer.

[procedure] (gnu-readline-read-history FILENAME)

Reads the history buffer from the file FILENAME (or ~/.history if FILENAME is #f). Returns 0 on success.

[procedure] (gnu-readline-write-history FILENAME)

Writes the history buffer to the file FILENAME (or ~/.history if FILENAME is #f). Returns 0 on success. Do not use unless you want to clobber simultaneous sessions.

[procedure] (gnu-readline-append-history FILENAME)

Appends only the new entries to FILENAME.

[procedure] (gnu-readline-new-lines)

Returns the number of new entries (input lines from this session).

[procedure] (gnu-readline-truncate-history FILENAME NUMLINES)

Truncates the history file FILENAME (or ~/.history if FILENAME is #f) to NUMLINES lines. Returns 0 on success.

[procedure] (gnu-history-install-file-manager FILENAME [NUMLINES])

If you also want to make the command history span sessions, add the following:

(gnu-history-install-file-manager (string-append (or (getenv "HOME") ".") "/.csi.history"))

By default this will save 1000 lines of history between sessions (it will prune the history file to 1000 lines at startup). For a different history size, pass the desired number of lines as the (optional) second argument to gnu-history-install-file-manager. If #f is passed in, no history-file-pruning will take place.

[procedure] (make-gnu-readline-port [PROMPT] [PROMPT2])

Returns an input-port that uses the GNU readline facility. If PROMPT is not given, the value returned by (repl-prompt) is used for generating the current prompt (see the Chicken manual for more details about repl-prompt). PROMPT2 is used when there are still unclosed parenthesis; if not given, an appropriate default is generated.

[procedure] (gnu-readline-set-bounce-ms TIME)

Changes the time that the cursor spends bouncing on the matching parenthesis - the default 500ms. To turn bouncing off completely, set to zero.

[procedure] (gnu-readline-parse-and-bind CONFIG)

Passes string CONFIG straight to the readline library for parsing (see the readline manual page for details). This extension supports static linking.


% csi -quiet
>>> (require 'readline)
>>> (current-input-port (make-gnu-readline-port "csi> "))

To get csi to keep a history use the following (in your ~/.csirc file):

(require 'readline 'regex)
(current-input-port (make-gnu-readline-port))
(gnu-history-install-file-manager (string-append (or (getenv "HOME") ".") "/.csi.history"))

To set readline to behave somewhat like vi:

(gnu-readline-parse-and-bind "set editing-mode vi")

Installation problems

This extension requires GNU readline. You will receive errors if you don't have the C header files for your readline installation or if you use some versions of the BSD readline alternative, libedit.


In particular, Mac OS X versions prior to 10.5 Leopard ship with /usr/lib/libreadline.dylib linked to an older libedit, causing the following error when you install this egg:

/usr/bin/ld: Undefined symbols:

To fix this, install a copy of GNU readline in /usr/local/lib or, if you're using MacPorts, symlink it:

ln -s /opt/local/lib/libreadline.dylib /usr/local/lib

Do not modify the readline link in /usr/lib.

MacOS X 10.5.2 again causes errors when building this egg. Installing MacPorts and doing the symlink above fixes the problem.

Debian GNU/Linux and derivatives (such as Ubuntu)

In the case of Debian, you should probably install the package libreadline-dev, which is not installed by default.

About this egg


Tony Garnock-Jones

Version history

Fixed history so that multiple sessions dont clobber each other. [elf]
Added proper signal handling [elf]
Added support for static linking [felix]
Ignores duplicate history entries [Thanks to Toby Butzon]
Empty lines are not added to history [Thanks to Dan Muresan]
Added parenthesis bouncing, a new auto-complete [Heath Johns]
Export *completion-entry-function* to support autocomplete [Alejandro Forero Cuervo]
prompt argument to make-gnu-readline-port is optional [felix]
Replaced use of (end-of-file) with #!eof
Checks more possible libraries to link with at build time [Thanks to Peter Bex]
Adapted to new setup scheme.
More features, changed license to GPL, links with either libtermcap or libncurses.
Initial release


Copyright (c) 2002 Tony Garnock-Jones
Copyright (c) 2006 Heath Johns (paren bouncing and auto-completion code)

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA