TweetFollow Us on Twitter

List Programming
Volume Number:1
Issue Number:6
Column Tag:LISP LISTENER

MACINTOSH List Programming

By Andy Cohen

Welcome to The Lisp Listener Window! This is the first of what we hope will become a regular column on programming Lisp on the Apple Macintosh. Lisp stands for List Programming and it is used for a very special type of computer programming in a field typically refered to as Artificial Intelligence or AI. Over the past five years AI has become a very popular and controversial topic. It has roots in Computer Science and Cognitive Psychology. The Psychologists found ways of describing human mental processes and the computer scientists have programmed these processes into computers, thereby getting the computer to perform human-like processing tasks.

Computers however, are definitely not one to one analogies to people. Computers process data. Human processes, on the other hand, deal with concepts. Lisp was designed specifically to handle the coding of these concepts by providing an object oriented, programm- ing environment. This development has provided us with programs that generate information by mimicking the same form of inductive reasoning as a person. In the case of specialized knowledge domains, these programs have been called Expert Systems. I will eventually try to emphasize on Lisp examples which will.

Take advantage of what makes Lisp different from the other languages covered in this publication. That is, it’s ability to manipulate objects, rather than just data, in a fashion similar to the way people do.

Is Lisp on the Mac Serious?

A friend asked me a little while ago if we will be able to program serious AI applications using Lisp? My first reaction was that we can’t. The smallest development system for an AI application has quite a bit more random access memory (from two to five Mbytes) and usually has a hard disk with more then 30 megabytes of space on which to read or write. The best we can hope for in the Macintosh environment (at the time this article was written!) is one megabyte of RAM and ten megabytes on a hard disk using the Mac XL. However, I also noted that sometimes the application is only developed using Lisp and then when finalized, the code is translated into a lower level language, such as Fortran. This recoding is done for speed and compactness.

My secondary feelings were yes, we probably can develop an AI application on the Mac to some extent, but the program will have to be translated into Pascal, C or even 68K Assembly. As it turns out, the version of Lisp coming from Expertelligence will allow us to do quite a bit with just 512K and two floppies. I’ll describe this package in detail later. Will we be able to use the Mac as an AI development machine? I am still sceptical, however I have a feeling that time will show us that it just might be possible. If you are asking, why would somebody program Lisp on the Mac at this time? I can only say one should use Lisp on the Mac for educational purposes. Heck, educational purposes are more than enough considering that a complete Lisp development system can cost over $75,000.00! Also consider that just a couple of years ago having Lisp on a micro-computer was almost as fictional as verbally asking your Mac to open the pod bay doors.

Different Lisps

Lisp comes in many different versions just like any other computer language. There is Zetalisp, Interlisp, Maclisp (not Macintosh) and some I’m sure I’ve never heard of. The versions of Lisp that are or will be available on the Macintosh are very close to Common Lisp. An excellent text for Common Lisp is “Lisp” 2nd ed. by Winston and Horn. All that I discuss in this article regarding Common Lisp follows what is in that text.

At the time this article was written only one version of Lisp was available. It is called XLisp and was developed by David Betz. It was programmed in C and was considered by Betz as an experimental language. There are two versions of XLisp that I have seen on the Mac; version 1.2 and version 1.4. Both versions of XLisp are interpreted. Only version 1.4 however, can handle object oriented programming. Unfortunately, XLisp 1.4 takes up most of the available memory on a 128K Mac. Either version of XLisp however, will work fine on a 128K Mac for demonstrating some of the arithmetic functions in Common Lisp syntax. The biggest advantage of XLisp is that it is Public Domain software. In other words, it is free. Look for it on Compuserve’s MAUG or to your local users’ group. Chances are it is available in one or more versions.

Lisp and Arithmetic

Enough small talk ( oops, sorry about that!) , now lets take a first look at Lisp. The most fundamental object in Lisp is an Atom. The atom is used in groups to produce Lists. Atoms and lists make up what are called expressions.

Okay, lets get a little more detail. A procedure specifies how something is performed. For example “+” or plus sign is a procedure. The “+” by itself is called a primitive. Numbers or symbols are refered to as arguments. Therefore the numbers 2.56 and 8.34 are arguments. These elements or atoms can be placed into a List:

 (+ 2.56 8.54)

The procedure “+” will then operate on the arguments 2.56 and 8.54 to produce 11.1. A bunch of procedures which work together are a program. More examples of lists are the following:

 (+ 2 2)
 (* 103 346)
 (/ 35 46)

If you have XLisp try typing these in yourself. The answers are produced when the carriage return is made, then displayed beneath the list. I used bold lettering to indicate the output.

 (+ 2 2)
 4

See. Isn’t that easy? Lets make things more interesting. Procedures can also be more complex, e.g. MIN and MAX (If you are trying this with XLisp be sure to use the lower case):

 (MIN 53 37 95 23)
 23
 (MAX 74 37 49 20)
 74

MIN will print the smallest argument in the list. MAX will print the largest.

One can also use primitives typically used with multiple arguments with singular arguments.

 (- 7)
 -7
 (- -3)
 3

In the first case the negative or subtract symbol turns the argument into a negative equivalent. In the second the “-” turns the negative argument into a positive just as -1*-3=3.

Lists can contain other lists.

 (- (* 4 9) (+ 8 32))
 -4

The equivalent of the above is as follows:

 (- 36 40)
 -4

As we can see the list is organized and performed in a typical hierarchical manner. A list, therefore, is made up of a left parenthesis, followed by any number of atoms or lists and concluded with a right parenthesis.

Dissecting Lists

Enough of numbers, lets start to use symbols as arguments.

 (A B C)

or

 (Alpha Beta Cookies)

Now lets use more sophisticated procedures. CAR and CDR are used to pull arguments out of lists. I’m told CAR stands for “Contents of Address Register” and CDR stands for “Contents of Data Register”. I’m sure there is some meaning in these titles with regard to the result, but that’s not important right now. What is important is what these procedures do.

(CAR ‘(Alpha Beta Cookies))
 Alpha

CAR returns the first argument in the list. Note that we are using a list in a list.

(CDR ‘(Alpha Beta Cookies))
 (Beta Cookies)

CDR returns the list minus the first argument. What if I am looking for the second argument in a list of three? In this case the CAR and CDR procedures can be nested.

(CAR (CDR ‘(Alpha Beta Cookies)))
 Beta

In the above example CDR produces the list,

 (Beta Cookies)

then CAR produces Beta. I hope you’ve noticed the single quote after the CDR above as well as in the other samples. This is how Lisp knows that the CDR in the above sample is a procedure and not just another argument. Without the single quote the following would be the result:

(CAR (CDR (Alpha Beta Cookies)))
 CDR

CDR in this case was not considered by Lisp as a procedure. The CAR procedure looked to the first argument, in this case the CDR, and displayed it. After playing a bit with these two procedures and a bunch of arguments one can see ways of making sets of procedures which will perform specific kinds of searches.

I’ve tried to give a very brief introduction to Common Lisp simply for the purpose of giving some impression of what Lisp looks like. Most of the above can be done using XLisp. Since Xlisp is an experimental program and Experlisp from Expertelligence will be a relatively serious Lisp development package, this column will probably deal exclusively with Experlisp. Next month The Lisp Listener Window will give a detailed description of Experlisp as well as discuss composing nested CARs and CDRs, symbolic assignment and a whole bunch of related procedures. In future installments I would like to review detailed examples as well as compare the performance of our little Mac to those of the Lisp machines from Xerox and Symbolics.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Trend Micro 11.0.2062 - An essential sec...
Trend Micro Antivirus provides essential security for macOS with real-time malware detection and mitigation in an affordable solution with a simple, intuitive interface. However, be aware that more... Read more
Backblaze 7.0.2.490 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac. With unlimited storage available for $6 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Pro Video Formats 2.2.1 - Updates for pr...
Pro Video Formats includes support for the following professional video codecs: Apple Intermediate Codec Apple ProRes AVC-Intra 50 / 100 / 200 / 4:4:4 / LT AVC-LongG XAVC XF-AVC DVCPRO HD HDV XDCAM... Read more
Boom 3D 1.3.11 - $19.99
Boom 3D is a revolutionary app with 3D Surround Sound and phenomenally rich and intense audio that is realistic and works on any headphones. Features 3D surround sound Built-in audio player... Read more
Final Cut Pro 10.5.2 - Professional vide...
Redesigned from the ground up, Final Cut Pro combines revolutionary video editing with a powerful media organization and incredible performance to let you create at the speed of thought.... Read more
Chromium 89.0.4389.72 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 89.0.4389.72: Complete list of changes can... Read more
iMovie 10.2.3 - Edit personal videos and...
With a streamlined design and intuitive editing features, iMovie lets you create Hollywood-style trailers and beautiful movies like never before. Browse your video library, share favorite moments,... Read more
OmniPlan 4.2.5 - Professional-grade proj...
With OmniPlan, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success,... Read more
Compressor 4.5.2 - Adds power and flexib...
Compressor adds power and flexibility to Final Cut Pro X export. Customize output settings, work faster with distributed encoding, and tap into a comprehensive set of delivery features. Features:... Read more
Motion 5.5.1 - Create and customize Fina...
Motion is designed for video editors, Motion 5 lets you customize Final Cut Pro titles, transitions, and effects. Or create your own dazzling animations in 2D or 3D space, with real-time feedback as... Read more

Latest Forum Discussions

See All

Frogger in Toy Town's latest update...
Konami Digital Entertainment has announced today that their Apple Arcade title Frogger in Toy Town has been updated to introduce a new ranked Endurance Mode. This new game variant's arrival is also accompanied by a few other changes. [Read more] | Read more »
Mitoza is surreal adventure toy you can...
The folks behind the Rusty Lake games have just put a new title onto the App Store. Second Maze, Rusty Lake's collaborative publishing brand, has just brought this 10 year old adventure game from Gal Mamalya to mobile. The best part about all of... | Read more »
Pocket Gamer Awards 2021: You have five...
Three weeks ago our sister site, Pocket Gamer, entered the voting stage for the upcoming Pocket Gamer Awards 2021 and is now in the final stretch. You only have a few hours left to vote for the games you’ve enjoyed on mobile in the past year, as... | Read more »
Patty Stack is a casual arcade game, ava...
Patty Stack is a casual arcade title that's available now for iOS and Android. It's the debut game from developer Feeka Games tasks players with making an increasingly giant burger tower. Think of it as Tower Bloxx but more edible. [Read more] | Read more »
Distract Yourself With These Great Mobil...
There’s a lot going on right now, and I don’t really feel like trying to write some kind of pithy intro for it. All I’ll say is lots of people have been coming together and helping each other in small ways, and I’m choosing to focus on that as I... | Read more »
Genshin Impact Guide - Gacha Strategy: W...
This is part 2 of our Genshin Impact gacha strategy guides. See part 1 here. You can check out more guides for Genshin Impact here. | Read more »
Slashy Camp is a new endless runner insp...
Blue Wizard Digital has released Slashy Camp onto iOS and Android after it spent a short amount of time in early access. [Read more] | Read more »
Kinder World is a relaxing game about lo...
Lumi Interactive is releasing a game called Kinder World later this year on iOS and Android, which is all about looking after houseplants. [Read more] | Read more »
Steam Link Spotlight - Fights in Tight S...
Steam Link Spotlight is a feature where we look at PC games that play exceptionally well using the Steam Link app. Our last entry was on Hades. Read about how it plays using Steam Link over here. | Read more »
Lyxo, the light-based puzzler for mobile...
Vienna-based independent game studio Emoak has just released its unique light-based puzzler for iOS and Android. Founded in 2014 by Tobias Sturn, the company is also the creative force behind the infinite climbing game Paper Climb, as well as the... | Read more »

Price Scanner via MacPrices.net

Weekend Sale: $100 off Apple iPad Magic Keybo...
Amazon has Apple iPad Magic Keyboards on sale for $100 off MSRP for a limited time. Amazon’s prices are the lowest available for iPad Magic Keyboard from any Apple reseller this weekend: – Magic... Read more
Gazelle now offering a full line of refurbish...
Gazelle is now offering a full range of discounted, refurbished, unlocked Apple iPhone 12 models starting at $649. iPhones are offered in Fair, Good, and Excellent conditions, and multiple colors are... Read more
These are the latest discounted iPhones Apple...
Apple has a range of Certified Refurbished iPhones available right now starting at only $339. Apple includes a standard one-year warranty, new outer shell, and shipping is free. According to Apple, “... Read more
Save up to $64 on new M1 MacBook Airs at Expe...
Apple reseller Expercom has 2020 13″ M1 MacBook Airs on sale for $51-$64 off Apple’s MSRP with prices starting at $947.96. In addition to their MacBook Air sale prices, take $50 off AppleCare+ when... Read more
Discounts available on 16″ MacBook Pros with...
Upgrade a 16″ 6-Core or 8-Core MacBook Pro from 16GB of standard RAM to 32GB at Adorama, and save $100-$210 over Apple’s price for this custom option: – 16″ 6-Core MacBook Pro/32GB RAM: $2699, save $... Read more
10.9″ iPad Airs on sale for $50-$70 off Apple...
Amazon has new 2020 10.9″ Apple WiFi iPad Airs in stock and on sale today for up to $70 off MSRP with prices starting at $549. Note that Amazon’s sale price might be restricted to certain colors (see... Read more
Apple restocks 2020 27″ 5K iMacs for up to $3...
After an initial offering in January, Apple has restocked a full line of Certified Refurbished 2020 27″ 5K iMacs starting at $1529 and up to $350 off original MSRP. Apple’s one-year warranty is... Read more
Sale! 16″ 8-Core MacBook Pro for $2449, $350...
Apple reseller Adorama has the 16″ 2.3GHz 8-Core Space Gray MacBook Pro in stock and on sale today for $2449 including free shipping. Their price is $350 off Apple’s MSRP for this model, and it’s the... Read more
Roundup of 13″ Multi-Core Intel MacBook Pro s...
Apple resellers are offering significant sales & deals this week on 2020 13″ MacBook Pros with 10th generation Intel CPUs. Take up to $250 off Apple’s MSRP, get free fast shipping, and/or pay no... Read more
64GB iPhone 8 Plus available for $379 at Appl...
Apple has the 64GB iPhone 8 Plus in Space Gray & Gold colors available for $379 today, Certified Refurbished. Each phone is unlocked and comes with Apple’s standard 1-year warranty and free... Read more

Jobs Board

Geek Squad Advanced Repair *Apple* Professi...
**795178BR** **Job Title:** Geek Squad Advanced Repair Apple Professional **Job Category:** Store Associates **Store Number or Department:** 001406-Allen Park-Store Read more
Geek Squad *Apple* Consultation Professiona...
**796549BR** **Job Title:** Geek Squad Apple Consultation Professional **Job Category:** Store Associates **Store Number or Department:** 001800-Hot Springs-Store Read more
*Apple* Mobility Specialist - Best Buy (Unit...
**796014BR** **Job Title:** Apple Mobility Specialist **Job Category:** Store Associates **Store Number or Department:** 001776-Woodmore Towne Centre-Store **Job Read more
Systems Architect, *Apple* Production Engin...
…package beginning on your first day? If so, we hope you'll keep reading! The Apple Sales Engineering and account team is looking for a stellar presales engineer with Read more
Systems Engineer, Webscale, *Apple* Retail,...
…beginning on your first day? If so, we hope you'll keep reading! The Apple Sales Engineering team is looking for a pre-sales engineer with Enterprise engineering Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.