How to Hack on lem Itself

There are two ways to hack on/develop Lem:

Work on Lem from Lem, on the same process.
Start a Micros server on Lem (Lem’s fork of Swank), connect to it from another Micros client.

Hack with Lem

Self connect from Lem

M-x start-lisp-repl

This will open a connection to Lem itself. All Lem systems and packages are loaded and available.

The only problem with this approach is that if you are tweaking some internal features it may broke the current editor, so be careful.

Start a Micros server from Lem

Micros is Lem’s fork of Swank.

M-x start-lisp-repl
CL-USER> (micros:create-server :dont-close t)

Next, connect to it from the outside.

Start another Lem instance and connect

M-x slime-connect

Hack with another editor

Start a Micros/Swank Server from Lem

M-x start-lisp-repl
CL-USER> (swank:create-server :dont-close t)

Connect from your editor

M-x slime-connect

Using this method, it is safe to break Lem because the editing process is separate from the main Lem process.

How to load Lem (into your Lisp image)

The project’s instructions show how to load and run Lem with Roswell. Here’s how we can do without, with a regular SBCL REPL and Quicklisp.

This was tested on LinuxMint, with SBCL 2.14 from Roswell and a recent enough Roswell Quicklisp dist (ros update quicklisp).

Clone the repository with git submodules:

git clone --recursive <url to lem>

Lem uses an asd file for each of its submodules, so you can’t compile the main lem.asd and quickload it. You need to set CL_SOURCE_REGISTRY=/path/to/lem// before starting the repl. Two slashes at the end tell ASDF to search asd files in subdirectories.

$ cd lem/
$ CL_SOURCE_REGISTRY=$(pwd)// rlwrap sbcl
* (asdf:load-asd "/path/to/lem.asd")
* (ql:quickload "lem")
[…]
* (lem:lem)
[… builds and runs the ncurses frontend …]

Load the SDL2 frontend:

* (ql:quickload "lem-sdl2")

To build a binary, see the following section.

Building lem

From the root directory of the Lem project, use Make.

with ncurses:

make ncurses

with sld2:

make sdl2

with both:

make sdl2-ncurses

This creates a binary in the root of the Lem project called lem.

Where to find debug logs

If you have problems launching Lem (maybe for a display error), the Lem function has a nice parameter to log the information into a file:

CL-USER> (ql:quickload :lem)

CL-USER> (lem:lem "--debug" "--log-filename" "lem.log")

This should save the logs in the file “lem.log” from the directory that the the REPL was launch.