Femto is an extended version of Atto Emacs with a tiny Lisp extension language.
A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint-Exupery
Femto comes with Markdown and HTML documentation. To rebuild the documentation Pandoc is required. Rebuild both documentation formats from their respective source files by running:
make doc
The documentation is prebuilt in this repository and can be found in
See the roadmap for future directions.
- To be an extendable version of the Atto Emacs editor using a Tiny Lisp extension language
- Provide a number of useful extension packages written in fLisp (these include an interface to git (similar to GNU Emacs Magit), a small version of dired, a buffer management menu (buffer menu), defmacro allows for a macro to be recorded and invoked using c-x e, and an interface to grep.
- Be easy to understand without extensive study (to encourage further experimentation).
As far as I know Femto is the only Emacs style editor to provide a macro recorder that generates usable Lisp code that can then be used to build a larger, more complex utility. Whilst GNU Emacs has a macro recorder facility it only allows you to dump out the keystrokes used during macro recording. Femto does this by writing the lisp code to a text buffer called macro. Though I have tried dozens of text editors over the years (mostly on PCs, but a few on mini and mainframe computers) I am not aware of any other editor that works this way. This feature was born out of the principle of keeping a small editor code written in C and where possible using Lisp to implement new features. The standard Emacs macro keystrokes [C-x (, C-c ), C-x e] are all written in Lisp in the file examples/defmacro.lsp. This meant that no special C code was needed in Femto to know when it was in macro mode or not.
The small Emacs naming scheme appears to use sub-unit prefixes in decending order with each further reduction of functionality. The Nano and Pico Emacs editors have been around for a while.
- Nano means 10 to the power of minus 9
- Pico means 10 to the power of minus 12
- Femto means 10 to power of minus 15
- Atto means 10 to power of minus 18
- Zepto means 10 to the power of minus 21
- Zep is smaller version of Zepto Emacs
In Defining Atto as the lowest functional Emacs I have had to consider the essential feature set that makes Emacs, 'Emacs'. I have defined this point as a basic Emacs command set and key bindings; the ability to edit multiple files (buffers), and switch between them; edit the buffers in multiple windows, cut, copy and paste; forward and reverse searching, a replace function and basic syntax hilighting. The proviso being that all this will fit in less than 2000 lines of C.
Femto is an extended version of Atto Emacs with its own extension language fLisp and less then 12.000 lines of C and Lisp.
- In late 2015 Hugh Barney wrote the Atto editor 'A minimum functioning Emacs in less than 2000 lines of C'. Atto was based on Anthony Howe's editor (commonly known as Anthony's Editor or AE, [2]).
- Femto is based on the Atto codebase [0]
- Femto was originally an intermediate project to form a codebase for the FemtoEmacs Editor [8], [9] which was a collaboration between Hugh Barney, Ed Costa and Lucas Guerra. FemtoEmacs uses Jeff Bezanson's Femtolisp LISP [10] implementation as the basis for its extension language. However the Femtolisp codebase is in excess of 12K line of code and fairly difficult to understand how to use it inside an embedded application.
- In late 2016 Hugh Barney decided to look for a smaller lisp implementation for Femto and settled on Tiny-Lisp[7] by Mattias Pirstitz.
- Zepl was an initial project that established the suitability of Tiny-Lisp for use within an Emacs type editor. The results surpassed expectations.
- In late 2017 Hugh Barney decided to return to the Femto editor and extend it using Tiny-Lisp.
- In 2023-2026 Georg Lehner refactored the Lisp infrastructure and started to fix and add additional Emacs functionality.
For a full version history please refer to the file CHANGE.LOG.md for past and future plans see the Femto
Femto has almost the same level of editor functionality as MicroEmacs 3.10 plus a fully featured Lisp extension language for a codebase less then half of the size.
Editor Binary BinSize KLOC Files
atto atto 33002 1.9k 10
pEmacs pe 59465 5.7K 16
Esatz-Emacs ee 59050 5.7K 14
femto femto 166472 7.4k/2.4k 36/10 **
GNOME GNOME 55922 9.8k 13
Zile zile 257360 11.7k 48
Mg mg 585313 16.5K 50
uEmacs/Pk em 147546 17.5K 34
Pico pico 438534 24.0k 29
Nano nano 192008 24.8K 17
jove jove 248824 34.7k 94
Qemacs qe 379968 36.9k 59
ue3.10 uemacs 171664 52.4K 16 ++
GNUEmacs emacs 14632920 358.0k 186
** KLOC: C / Lisp lines
Files: total files / fLisp only files.
Since Femto 2.12 C code is being moved out to Lisp, since Femto 2.25 fLisp has been moved out of the Femto source tree.
Note: this is the README for the unofficial Femto 2.25.* releases. All
relevant links point to the Github account jorge-leon, all credits
go the original author hughbarney.
Debian and Ubuntu:
Before ncurses 6 and as of Femto 1.2 you will need to install the libcurses dev package.
$ sudo apt-get install libncurses5-dev libncursesw5-dev pgkconf
Since ncurses 6:
$ sudo apt-get install ncurses-dev pkgconf
Alpine Linux:
$ sudo apk add ncurses-dev pkgconf
NetBSD:
$ doas pgkin install ncurses pkgconf
FreeBSD:
$ doas pkg install devel/ncurses pkgconf
Since Femto 2.25 fLisp is split out into its own source tree so it has to be installed separately.
From source:
git clone https://github.com/jorge-leon/flisp
cd flisp
make
sudo make install-dev install-libOr download suitable flisp-dev and flisp-common Debian Packages
from https://github.com/jorge-leon/flisp/releases and install them with
sudo dpkg -i flisp-dev_*version*_*arch*.deb flisp-common_*version*_*arch*.deb
$ git clone https://github.com/jorge-leon/femto.git
$ cd femto
$ git switch femto-fixes
$ make femto
$ make test
$ sudo make install
Prebuilt packages for Debian and Alpine Linux are available.
Alpine Linux provides femto in the "testing" repository. Versions lag some months behind releases.
See the coding style guide.
Pandoc and tidy is required for doc generation.
- Debian/Ubuntu:
sudo apt-get install pandoc tidy - Alpine:
sudo apk add pandoc-cli tidyhtml - NetBSD:
doas pkgin install pandoc-cli tidy - FreeBSD:
doas pkg install hs-pandoc tidy-html5
There is a Doxyfile to create full cross references and call graphs.
Usefull build targets:
femto: build femto binarydoc: build some markdown files from Poshdoc and some html files from markdowndoxygen: build the Doxygen source code documentationmeasure: count # of files and code linestest: run unit tests in summary modecheck: run unit tests and return success if none failsftest: call femto several times with different commandline parameters.val: run femto with valgrind. Logs are found in val.logclean: clean up build artifactsdeb: build Debian packageinstall/uninstall: install/uninstall locally
Make sure to run:
make clean test
make clean ftest
make clean doc
before commiting code to Github.
Note: build on NetBSD and FreeBSD is currently not working.
Femto code is released to the public domain. hughbarney@gmail.com November 2017, jorge@magma-soft.at 2023
- [0] Atto Emacs - https://github.com/hughbarney/atto
- [1] Perfect Emacs - https://github.com/hughbarney/pEmacs
- [2] Anthony's Editor - https://github.com/hughbarney/Anthony-s-Editor
- [3] MG - https://github.com/rzalamena/mg
- [4] Jonathan Payne, Buffer-Gap: http://ned.rubyforge.org/doc/buffer-gap.txt
- [5] Anthony Howe, http://ned.rubyforge.org/doc/editor-101.txt
- [6] Anthony Howe, http://ned.rubyforge.org/doc/editor-102.txt
- [7] Tiny-Lisp, https://github.com/matp/tiny-lisp
- [8] FemtoEmacs, https://github.com/FemtoEmacs/Femto-Emacs
- [9] FemtoEmacs, https://github.com/hughbarney/Femto-Emacs
- [10] Femtolisp, https://github.com/JeffBezanson/femtolisp