Pieces tagged with: lisp

May 10, 2022

lisp asdf

Switch the current working directory in the REPL

If you start a REPL in the wrong directory, you can switch it by using UIOP.

UIOP is the portability layer of ASDF, supplying an abstraction on top of different implementations or OS'es.

For example, to change to a new project do:

(uiop:chdir "~/lisp/fangorn/")

Make your own packages available to Quicklisp

In Lisp it's quite common to have your own helper libraries, which are packaged as ASDF packages. To be able to use your libraries in other projects, you need to let ASDF know how to find them.

First create the directory ~/.config/common-lisp/source-registry.conf.d/

There create a file with any name of your choice but with the type conf, for instance 50-petar-lisp.conf.

In this file, add the following line to tell ASDF to recursively scan all the subdirectories under /home/petar/lisp/ for .asd files: (:tree "/home/petar/lisp/").

May 9, 2022

lisp

Template for a new Common Lisp Project

To easily start a new Common Lisp project, I'm making use of the CL-Project from the famed Lisper Eitaro Fukamachi.

You can either install it through roswell with ros install cl-project or through the use of Quicklisp with ql:quickload "cl-project").

The benefit of install it through Roswell is that you also get a binary.

To create a project through the REPL:

(cl-project:make-project #p"lisp/cl-sample/"
  :author "Eitaro Fukamachi"
  :email "e.arrows@gmail.com"
  :license "LLGPL"
  :depends-on '(:clack :cl-annot))

Or by using the binary:

make-project /home/user/common-lisp/sample \
    --name sample \
    --description "sample project." \
    --author "Your name" --license LLGPL \
    --depends-on alexandria split-sequence`

November 15, 2021

lisp ai

From Lisp to Python, but why Peter?

Peter Norvig is a well-known educator on A.I. and used to be one of the key figures in the Lisp movement.

His books used to use Lisp in their exercises, but he switched to Python at some point. Today, I came across the Lex Fridman podcast, where he interviewed Peter Norvig and asked him why he made that change.

He gives a surprisingly simple answer at the 43-minute mark.

I was expecting deeper reasons, but his students were having difficulty grasping Lisp, and a questionnaire showed that Python mimicked the pseudocode from the book the most. That's it.

In the short amount of time he had to educate them on A.I., he could not spare the time to educate them on Lisp.

Coincidentally, I also came across this gem at smuglispweeny blog:

At ILC 2002 former Lisp giant now Python advocate Peter Norvig was for some reason allowed to give the keynote address like Martin Luther leading Easter Sunday mass at the Vatican and pitching Protestantism because in his talk Peter bravely repeated his claim that Python is a Lisp.

When he finished Peter took questions and to my surprise called first on the rumpled old guy who had wandered in just before the talk began and eased himself into a chair just across the aisle from me and a few rows up.

This guy had wild white hair and a scraggly white beard and looked hopelessly lost as if he had gotten separated from the tour group and wandered in mostly to rest his feet and just a little to see what we were all up to. My first thought was that he would be terribly disappointed by our bizarre topic and my second thought was that he would be about the right age, Stanford is just down the road, I think he is still at Stanford -- could it be?

"Yes, John?" Peter said.

I won't pretend to remember Lisp inventor John McCarthy's exact words which is odd because there were only about ten but he simply asked if Python could gracefully manipulate Python code as data.

"No, John, it can't," said Peter and nothing more, graciously assenting to the professor's critique, and McCarthy said no more though Peter waited a moment to see if he would and in the silence a thousand words were said.