Lisp is one of the most ancient high-level languages still being used today. It appeared in 1958 when the computer occupied an entire room and many people had never seen one. Four decades later, and it’s still being written, debated and (some of them) loved.
There are, then, questions why the lisp programming language is still relevant to today’s computing that have to do with ideas. Lisp was the language in which they invented garbage collection, recursion, and treating code as data — before they became common in other languages. Many of the things you’re using in Python or JavaScript are somewhat lispy.
Now let’s examine what Lisp is, where it originated and how it’s applied. We’ll also briefly discuss some simple code examples and how that relates to AI.
What Is Lisp Programming Language?
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Lisp is a programming language based on lists. The name is derived from “LISt Processing” and that is the essence. Your data, and your code, is both represented as a list surrounded by parentheses in Lisp.
On the surface, that doesn’t seem to make sense. You’ll see brackets in brackets and everybody puns on it all the time. After a bit, it’s not that hard, and it’s really one pattern to learn, the structure becomes simple and consistent.
If someone asks you about the lisp programming language, the short answer is “it’s a family, not a single language,” and each one has this lisp idea of a list.
Lisp Programming Language Core Features
Lisp is not a language that has many features, but it has enough and they’re all tightly integrated. The most prominent ones are detailed below.
1. S-expressions – All Lisp code is in the form of a list in parentheses. Typically, the first line will be the action and the remaining lines the things the action works on. It’s one pattern, so there’s not much syntax to learn.
2. Homoiconicity – Big word simple idea. In your code, and in your data, you have the same kind of objects, both are lists. This implies that a program in Lisp can easily read, modify and even write Lisp programs.
3. Macros – You can write your own chunks of syntax using macros. Rather than having to wait for the language to add a feature, you just create it yourself. One of the main reasons people continue using Lisp for so many years.
4. Dynamic typing – No need to declare the types in advance. Lisp will figure it out as it runs, making it easy to test out ideas in a quick manner, and less annoying..
5. Garbage collection – Lisp is garbage collection friendly – you don’t need to worry about manually doing garbage collection. It was one of the first languages to do this.
| Also Read: If you’re curious about which languages actually pay the most, check out our guide on the highest paying programming languages before you pick what to learn next. |
Lisp Programming Language History
The history of Lisp is one of the more interesting in computing, and goes back a long time before most people realize. Let’s take a walk down it.
The Origins: John McCarthy and MIT (1958)
Lisp was created by John McCarthy in 1958, while he was working at MIT. He was deeply involved in the study of early AI and required a language capable of manipulating symbols and logic, not just numbers. The languages of that time were mostly geared towards math, so he thought of something different.
It was actually supposed to be more of a theory and not a working language, the first one. The ideas McCarthy had were implemented a student named Steve Russell took a look at them and decided to make them a real program and it did. That’s when Lisp got from paper to computer. It was made the second oldest high level language still in use after Fortran.
Major Dialects and Their Evolution
As time went on, Lisp evolved into a number of variants or dialects. They were all different in style and for a different purpose.
Common Lisp – Was brought together in the 1980s to unify all the various versions of Lisp. It’s large and rich in features.
Scheme – Created in the 1970s at MIT. It is small and clean and it is commonly used in learning.
Emacs Lisp – The programming language in which the Emacs text editor is customisable. Lots of people learn it without even planning to.
Clojure – Released in 2007. It is used for modern, data rich projects and is written on the Java platform.
Lisp Programming Language Example and Code
The best way to learn Lisp is to look at some. If the parentheses don’t make sense at first, that’s okay, we’ll go through each example slowly.
Basic Syntax Explained
Lisp employs a form of writing that is known as prefix notation. This simply means that the action is first, and the things that it works upon are at the end. So instead of writing 2 + 3, you write it like this: (+ 2 3).
All of the terms are enclosed in parentheses. The first one is the function (the action), and the others are the inputs. After you learn this one rule, you will be able to read most Lisp code.
Simple Lisp Code Examples
1. Hello World
| (print “Hello, World!”) |
The text is inside the quotes, print is the function, and it will print the text on the screen.
2. Arithmetic Operations
| (+ 5 3) ; gives 8 (* 4 6) ; gives 24 (- 10 2) ; gives 8 (/ 20 4) ; gives 5 |
The format of each line is the same; numbers come at the end and their operator is at the start. The text following the semicolon is a comment, and is ignored by Lisp.
3. Defining a Function (Factorial)
| (defun factorial (n) (if (<= n 1) 1 (* n (factorial (- n 1))))) (factorial 5) ; gives 120 |
Here, defun is creating a new function called factorial. If it’s 1 or lower, it will return 1. Otherwise, it takes the number below it, and calculates its factorial. Recursion, that’s what it is and Lisp is quite at home with it.
4. Working with Lists
| (setq fruits ‘(“apple” “banana” “cherry”)) (first fruits) ; gives “apple” (rest fruits) ; gives (“banana” “cherry”) (length fruits) ; gives 3 |
A variable is used to store the list in setq. The little apostrophe that precedes the list, tells Lisp to treat it as data, not execute it. Then, you could retrieve the first one, the rest or the number of them.
What Is Lisp Programming Language Used For?
Lisp is not exactly the language most people would turn to on a Monday morning, but it’s still finding practical uses in a few select places. This is where you will be able to find it.
1. Artificial Intelligence and Symbolic Computing
This is where Lisp has been introduced. It was the foundation for the early AI programs that worked with symbols, rules and logic. Lisp was used for many things such as expert systems, natural language tools and early robotics projects. Its use is still seen in some research labs for the same reason – dealing with symbolic problems well.
2. Text Editors and Automation
Everybody who’s ever customized Emacs, has used Lisp, whether they intended to or not. The Emacs Lisp language allows people to customize virtually every aspect of Emacs and some people go so far as to use Emacs to automate routine tasks on a daily basis.
3. Data Analysis and Research
Lisp is a flexible language, can handle messy and uncommon data. It is sometimes picked up when a researcher wants to test out an idea quickly and modify it just as rapidly. Not as popular here as Python, but there are fans of it.
4. Web Development, Finance, and Startups
This is where the modern Lisp, Clojure, the Java platform language, flies the flag. Is suitable for use by some fintech companies and startups for back-end systems due to its ability to manage data effectively and maintain code efficiency.
Real-World Examples
- Emacs – One of the most famous editors, extended with Emacs Lisp.
- Grammarly – Has used Common Lisp for parts of its backend.
- Nubank – A large digital bank that uses Clojure across its systems.
- AutoCAD – Uses AutoLISP, a Lisp dialect, for custom scripts.
Why the Lisp Programming Language was a Big Deal (and Still Matters)
Ever since the dawn of time, there has been a close relationship between Lisp and AI. To answer the “why,” one must delve into the problem’s origins for the early AI researchers.
Why Early AI Researchers Chose Lisp
AI in the 1960s and 70s was not a matter of building massive amounts of data into models. It was all about reasoning with symbols, rules and ideas with computers. That’s why Lisp was invented. Everything was a list, so it was easy to represent statements such as “a cat is an animal” or “if this is true, then do that. The researchers did not have to struggle with the language to convey their ideas and this was a significant factor.
Where Lisp Really Shines
- Symbolic reasoning – Lisp natively supports symbol manipulation and logic, ideal for expert systems and rule-based programs.
- Typical of the rapid prototyping – you type a line, see what it does, and adjust it immediately. It’s nice if you’re still in the formulating phase.
- Code as data – Programmer can write & modify program using code itself (because code is just a list). That presents some very interesting possibilities in the realm of Artificial Intelligence research.
Is Lisp Still Relevant for AI Today?
Well, it’s not the primary anymore! The Python ecosystem came to the fore, led by packages such as TensorFlow and PyTorch, primarily due to its vast library of tools. Python is the actual choice for creating contemporary machine learning models.
But that’s not the end of Lisp! It still has some uses in areas of research such as symbolic AI and knowledge-based systems, and a lot of the concepts that which underpinned it are still alive today in the tools. It’s more about a platform that many thinking about AI activities were developed on, and less about a competitor.
Advantages and Disadvantages of the Lisp Programming Language
As with all languages, Lisp has its strengths, and its weaknesses. Let’s see the pros and cons of it so you know what you are in for.
Advantages of Lisp
- Flexibility – Lisp doesn’t impose any particular way of doing things. There are various ways to write it and alter the language to suit your problem.
- Great macros – Be able to build your own syntax and save tons of repeated code. It’s one of the few languages that allow you to do that so easily.
- Small chunks of code can be tested immediately – can change code on the spot – ideas come alive quickly.
- Longevity – It has been here since 1958 and still is. The basic concepts have worked out pretty well.
Disadvantages of Lisp
- Steep learning curve – List-based thinking and recursive functions are counterintuitive for someone not used to working with Python or Java.
- Parentheses all over the place – Yes, it’s a thing. The first few times you have to read code that’s deeply nested, it can be tiring, but a good editor can make it easier.
- Less popular – Fewer tutorials, libraries and jobs will be available than for popular languages and you may have to work harder to find support.
Final Thoughts: Is the Lisp Programming Language Worth Learning?
So, is the lisp programming language worth your time? It depends on what you want out of it. If your goal is to land a job fast, Python or JavaScript is probably the safer bet. But if you’re curious about how programming really works, Lisp is a great teacher. It changes how you think about code, and that sticks with you even when you go back to other languages.
Lisp is a good fit for students, curious developers, and anyone interested in AI research or language design. Give it a weekend, try the examples from this post, and see how it feels. You might end up liking it more than you expected.
Want to keep learning? Check out more programming and data science guides on Statanalytica.
FAQs
1. What is Lisp used for?
Lisp is mostly used for AI research, symbolic computing, and customizing the Emacs editor. Some startups also use Clojure, a modern Lisp, for backend systems and data work.
2. Is Lisp good for AI?
Yes, especially for symbolic AI and rule-based systems. It’s not the top pick for machine learning today, since Python has far more libraries, but Lisp still has its place.
3. Is Lisp still used today?
It is, just in smaller areas. You’ll find it in research, Emacs, some finance and tech companies, and in Clojure projects. It’s not popular, but it’s far from dead.
