Lisp (deriving from "List processing") is one of the oldest, yet still actively used programming languages in the world. Created in 1958, only a year after Fortran, Lisp pioneered some fundamental concepts in computer science like dynamic typing, tree data structures and automatic memory management, which influenced generations of languages.
While not as mainstream as languages like Java or Python today, Lisp continues to be a popular choice in areas like artificial intelligence, bioinformatics, 3D modeling and natural language processing. The family of languages descending from Lisp includes important ones like Common Lisp, Scheme and Clojure.
In this comprehensive guide, we will trace the origins of Lisp and how it evolved over decades, understand its core capabilities, examine its major dialects, bust some myths, and discuss its relevance today. We have tried to keep technical jargon to a minimum to make it accessible for beginners too. So let‘s start unraveling the history of one of most ingenious computer languages ever created!
A Brief History of Lisp
Lisp was invented in 1958 by John McCarthy, while he was at Massachusetts Institute of Technology (MIT). Inspired by Alonzo Church‘s lambda calculus model of computation, McCarthy wanted to create a practical mathematical notation for computer programs to solve problems in artificial intelligence.
The recursive functions required for AI problems aligned well with lambda calculus. So McCarthy devised a family of programming languages called Lisp or "LISt Processing" based on it. As one of the earliest high-level languages with dynamic typing, Lisp was a drastic departure from low-level, static languages like Fortran back then.
Over the next decade, Lisp grew rapidly beyond MIT – a dialect called Maclisp was developed in the 1960s and remains an influence on Common Lisp today. Another dialect BBN Lisp became popular for writing the first chatbot programs mimicking human conversation.
By 1970s, many prominent versions like Franz Lisp, Scheme and Standard Lisp were created for different applications and platforms. The 1980s saw another major Lisp dialect take shape – Common Lisp, attempting to standardize key features. Concurrently, Lisp also became the underpinning for algorithms powering the first expert systems deployed commercially.
In a testament to Lisp‘s flexibility, the 1990s spawned dialects that continue to thrive today like Emacs Lisp for scripting Emacs editor, AutoLISP for extending AutoCAD functionalities and ClojureLisp running on Java platform. While no longer as popular for AI compared to Python and Lua today, Lisp retains a strong cult following cutting across domains even 60+ years from its birth!
6 Key Features of Lisp
There are some signature traits that set Lisp apart from Fortran, COBOL, C and other contemporaries from 1950s-60s, many of which were either low-level languages or supported limited data types:
1. Lists as fundamental data structure: In Lisp, code itself is represented as a hierarchical tree of lists. So manipulating code as data comes naturally – this concept of homoiconicity influenced many future languages.
2. Prefix notation: All functions and operators come before operands in parentheses instead of infix (C, Python) or postfix (Forth) notations. This took time getting used to back then!
(* 3 (+ 4 5)) ; Multiplies 3 by sum of 4 and 5 3. Dynamic typing: Variables can hold data of any type instead of requiring pre-declaration of types like in statically typed languages. This flexibility supports rapid prototyping.
4. Automatic memory management: The runtime environment handles allocating memory for data and freeing it transparently once no longer required – programmers don‘t have to explicitly de-allocate memory as in C/C++. This paved the path for higher level languages.
5. Emphasis on recursion: Lisp utilizes recursive functions extensively compared to iteration via loops in Fortran/Algol-like languages. This recursive style was ideal for AI applications with trees/graphs data structures.
6. Code as data philosophy: Lisp treats code in the same way as any other data. This allows programs to easily manipulate other programs, enabling metaprogramming and language extensions.
These advanced concepts made Lisp incredibly flexible, expressive and well-suited for complex AI problems, symbolic computation and more. However it also gained a reputation of being quirky with all those parentheses!"
Over the decades, Lisp evolved into an umbrella of inter-related yet distinct dialects for different domains…
Major Dialects of Lisp
Like any language that has constantly reinvented itself across six decades, Lisp has had no shortage of offspring dialects. Here we cover a few influential ones that underline Lisp‘s adaptability:
1. Maclisp
Developed at MIT for the Multics OS in the 1960s, Maclisp took Lisp far beyond academia into mainstream. Its major additions like dynamic variables and binding paved the way for runtime environment in Common Lisp.
2. InterLisp
Created at BBN technologies for PDP-10 computers running Tenex OS, InterLisp aimed to make Lisp more accessible for programmers. It formed the basis of languages like Common Lisp and Scheme.
3. ZetaLisp
Also called Lisp Machine Lisp, it powered Symbolics‘ Lisp Machines – custom hardware & software environments tailored exclusively for Lisp in the 1980s. ZetaLisp helped scale Lisp apps for real-world deployment.
4. Scheme
A minimalist, elegant dialect designed in 1975, Scheme emphasized recursion and first-class functions powered by Lexical scoping. With a smaller set of core features, it remains popular in computer science education today.
5. Common Lisp
Merging key innovations from Maclisp, Lisp Machine Lisp and more, Common Lisp was a language unification effort started in 1984. Itcombined procedural, functional, object-oriented (CLOS) paradigms making Lisp far more versatile and mainstream.
6. Clojure
A recent Lisp dialect running on JVM platform, Clojure offers modern amenities like immutability-by-default, functional programming, concurrency support and interoperability with Java ecosystems. Released in 2007, it powers large-scale applications today.
Apart from above, Lisp also underpins scripting languages for extensible apps like Emacs Lisp, AutoLisp embedded in AutoCAD, Autodesk and multimedia tools. Other flavors like newval Lisp, Franz Lisp and more continue to evolve serving niche domains.
Now that we have seen the powers of Lisp and the breadth of dialects over six decades, let us tackle some common myths around it…
5 Myths around Lisp
Given its age and adaptability across the full spectrum – from tiny embedded apps to large always-on cloud services today, some misconceptions around Lisp linger…we debunk a few here!
Myth 1 – Lisp is not suited for modern software architectures
Reality: From expert systems in 1980s to scalable platforms like CloudLisp in 2010s, Lisp pioneered modular architecture, domain-driven-design and more. Macro systems make it adept for metaprogramming.
Myth 2 – It is only used in academia, not real products
Reality: Common Lisp powers mission-critical applications in aerospace, energy, fintech and tools like Grammarly. Industrial Lisp powers manufacturing automation using CAD and robotics.
Myth 3 – Lisp has been replaced by Python & Java for AI today
Reality: While no longer as popular, Clojure & Common Lisp integrate well with Python/Java for data processing pipelines. Unique features like homoiconicity still suit symbolic AI applications.
Myth 4 – Modern languages have caught up and surpassed Lisp‘s capabilities
Reality: Many contemporary languages draw ideas from Lisp but very few offer the same combination of code-as-data philosophy, homoiconicity, multi-paradigm support, metaprogramming capability, and syntactic flexibility crucial for specialized domains.
Myth 5 – Lisp is notoriously difficult to program in
Reality: The parentheses for S-expression look unfamiliar for beginners but most Lisp dialects offer great tools, documentation and community support today to ramp up. Powerful REPL environments help too.
Why Learn Lisp Programming
While not as mainstream outside specialized domains, Lisp unlocks unique capabilities even after 60+ years that make mastering it deeply rewarding:
1. Expressiveness – Concise syntax to translate complex problems into code using lists, trees, functions and macros.
2. Metaprogramming Power – Homiconicity allows easy manipulation of code as data to extend the language on fly for your apps.
3. Multi-paradigm – Procedural, functional, object oriented styles work seamlessly to model real-world entities and logic through a unified Lisp approach.
4. High Leverage – Features like automatic memory management, dynamic typing help solve gnarly problems fast.
5. Tried & Tested – Battle-hardened for decades powering mission-critical systems with rock-solid implementations.
For programmers looking to expand their mental models beyond popular OO and functional languages, delving into Lisp unlocks a whole new dimension of thinking about problems!
The conciseness and almost mathematical aesthetic of Lisp feels closer to the developer compared to verbosity demanded by production languages like Java and C#. It encourages you to think programmatically about every step required to solve challenges.
While the unique REPL environment, parentheses-happy syntax and pervasive use of lists, lambdas do impose their own learning curve, you emerge a significantly more well-rounded developer able to pick the right language for the job!
Getting Started with Lisp
Due to its longevity, Lisp offers multiple full-featured dialects to choose from depending on whether you need to interface with existing apps in Java or C ecosystems. Here are two dialects beginners can start with:
Common Lisp
Common Lisp offers a great balance of key features drawing from multiple lineages of Maclisp, Scheme, ZetaLisp and more. With robust implementations like SBCL (Steel Bank Common Lisp) and CCL (Clozure Common Lisp) powering industrial apps too, Common Lisp makes for a friendly, versatile starting point.
Step 1: Install SBCL or portable CCL on your OS
Step 2: Launch REPL and execute basic arithmetic like:
> (+ 2 3)
5
> (print "Hello World")
"Hello World" Step 3: Work through the excellent Common Lisp cookbook
Step 4: Build small scripts, utilities to get habituated
Step 5: Tackle projects on QuickLisp/Ultralisp leveraging packages
Clojure
A babylonic Lisp running on rock-solid JVM, Clojure offers modern amenities like immutability-by-default, functional programming and excellent concurrency to write robust concurrent apps sans threads.
Step 1: Install the latest Clojure build tools like Leiningen
Step 2: Follow a tutorial like Clojure basic tutorial for the absolute beginners
Step 3: Write functions to process collections like maps, vectors
Step 4: Try outconcurrency primitives like futures, promises
Step 5: Build microservices and APIs interacting with Postgres etc.
Common Lisp and Clojure make it easy to get started whether you care more about interacting with C libraries or Java infrastructure respectively. Scheme and Emacs Lisp also provide gentle on-ramps welcoming beginners.
Ideally, set aside 2-3 weekends for a quick-start without getting intimidated by the functional programming style or parentheses syntax – trust us, it is an immensely gratifying investment mastering such an iconic language!
The interactive environments help you tweak code rapidly to get hands-on instead of write-compile-run cycle in other languages. We could dedicate a whole section just for cool code snippets that highlight Lisp‘s expressiveness!
Real-world Usage of Lisp
Instead of providing abstract examples, let us walk through some real-world scenarios where Lisp delivers serious advantage even today:
Symbolic AI and Expert Systems
Seminal AI applications dealing with heuristic rules for medical diagnosis, mathematical theorem proving benefited immensely from Lisp‘s unique combination of code-as-data paradigm, flexibility with symbolic expressions and automatic memory management. Powerful pattern matching frameworks like CLIPS continue to empower modern expert systems.
Bioinformatics
Lisp‘s ability to elegantly represent and processes trees/graphs data structures made it ideal for bioinformatics apps especially in human genome sequencing, Protein interactions modelling and more. The Lisp-Stat language for statistical computing is invaluable today for data analysis.
3D Graphics & CAD
The extensibility offered by dialects like AutoLISP helped add custom functionality exactly when needed by engineers using AutoCAD for 3D mechanical modelling and designing everything from cars to skyscrapers. This tradition continues with Lisp-infused OpenSCAD language for CAD professionals.
Financial Trading platforms
From automated algorithmic trading systems to exchanges like NASDAQ, Lisp‘s legendary runtime performance, support for advanced math functions and quick alteration of business logic without downtimes provide a competitive edge to the financial domain. Lisp-based systems continue to power trading platforms processing billions of events per day.
Embedded scripting
For applications needing embedded logic or scripting, Lisp provides a safe, sandboxed environment to add capabilities keeping overall system intact. These embeddable dialects power a spectrum of tools – Emacs text editor via Emacs Lisp, Runtime modding of games through mobl MOBILEScript Lisp to scientific tools like Mathematica.
This by no means is an exhaustive list but provides a glimpse into the diversity of practical applications where various Lisp dialects deliver value owing to their closest proximity to the problem domain.
With modular designs and interoperability with other languages, Lisp continues to adapt and thrive supporting today‘s programming challenges!
The Future of Lisp
Turning 64 in 2022, Lisp seems more like fine wine than outdated tech! Its core focus on marrying code elegance with practical problem solving aligned perfectly all along with the rising paradigm of Software 2.0 – where domain-specific languages assist in easier development of systems.
With engines supporting everything from smart contracts to satellite imagery analysis now relying extensively on DSL, Lisp ideals are shining through! Lisp‘s sweet spot also remains AI and symbolic computation. So as we enter the stage where abstract reasoning, heuristics and explainability become crucial for AI safety and trust – Lisp offers wisdom drawn from its six decade rendezvous with deducing patterns in data.
The Lisp way of thinking trains developers in abstracting real-world systems as hierarchical trees of functions and data with bottom up reasoning – an invaluable skill increasingly rare among younger programmers used to modern languages nursing OO overdose!
So talk of Lisp‘s demise seems silly when arguably Software 2.0 can benefit tremendously from Lisp‘s domain agility, richness of composable features and most importantly the sheer multi-generational wisdom around solving complex problems simply!
Rather than treated as archaic tech, Lisp deserves recognition as the eternal elder luminary – reminding us to keep minimum friction between human thoughts and their faithful translation into code – an advice increasingly easy to forget amidst layers of cumbersome enterprise frameworks!
Conclusion
We hope this walkthrough gave you an accessible yet comprehensive overview of Lisp‘s origins, evolution, dialects and why it remains a source of invaluable wisdom for programmers entering the field today!
Instead of dismissing it as esoteric tech irrelevant for modern software, take time to dip into this multi-faceted language once through online courses or books – we promise the new modes of thinking and Lispesque zen you‘ll imbibe will profoundly influence how elegantly you sculpt future programs!
So learn Lisp, be humbled by its sheer longevity and most importantly have fun bending this playful language to elegantly solve problems – just like generations of programmers who fell in love with it over last 60+ years and counting!
