The Hidden Dominance of Functional Programming
When Simon Peyton Jones, one of the creators of Haskell and a researcher in functional programming, explains Excel, he frames it this way: “the easiest way to get at functional programming is to think of spreadsheets.” While the programming world often debates the merits of functional programming versus object-oriented or imperative approaches, functional programming has spread through mainstream computing in ways most users never notice.
Adoption Without a Name
Functional programming spread without academic persuasion and without converting many traditional programmers to languages like Haskell or OCaml. It became embedded in tools used daily by hundreds of millions of people who would never identify themselves as programmers at all. The paradigm reached that scale without most of its users ever knowing its name.
Excel: The World’s Most Successful Functional Programming Platform
Microsoft Excel is the clearest example of functional programming’s hidden reach. As Simon Peyton Jones noted in a 2021 Microsoft Research podcast, Excel has a functional language where formulas define the value of cells in terms of other cells, similar to how functions in Haskell or other functional languages define values in terms of other values.
“In a spreadsheet cell, you say, ‘Here is a formula that gives the value of a cell.’ And you compute the value of a whole spreadsheet full of cells by computing each cell, perhaps one at a time, perhaps in parallel, but in data dependency order,” explains Peyton Jones when describing the functional nature of spreadsheets.
The market reach of Excel as a functional programming environment is wide. In a presentation titled “Spreadsheets: Functional Programming for the Masses,” Peyton Jones highlighted that while there are approximately 2 million “classic” programmers who write code in languages like C++ and C#, there are an estimated 50 million end-user programmers who use Excel formulas to build models. These users aren’t professional programmers but rather engineers, teachers, financial analysts, and others who use Excel’s functional paradigm without even realizing it.
Recent innovations in Excel have enhanced its capabilities as a functional language. The introduction of LAMBDA functions in 2021 made Excel’s formula language Turing-complete, allowing users to define custom functions directly in the spreadsheet without resorting to VBA or other programming methods. As Brian Jones, head of product for Excel, notes: “there are orders of magnitudes more people that know how to write formulas, then know how to write JavaScript.”
Erlang: Functional Programming Powering Telecommunications
While Excel represents functional programming’s quiet dominance in business applications, Erlang demonstrates how functional programming has become essential infrastructure for global communications.
Developed at Ericsson in the late 1980s, Erlang was created specifically to handle the demanding requirements of telecom systems. According to Erlang’s official website, it was designed for “telecommunications applications, e.g. controlling a switch or converting protocols” and other systems requiring “distributed, reliable, soft real-time concurrent systems.”
The impact of Erlang on our daily lives is far greater than most people realize. At the Code BEAM Stockholm conference in 2018, Cisco revealed that it ships 2 million devices per year running Erlang, translating to approximately 90% of all internet traffic passing through routers and switches controlled by Erlang. Additionally, Ericsson uses Erlang at the core of its GPRS, 3G, 4G, and 5G infrastructure, with a 40% market share of mobile telecommunications equipment.
Erlang reached this scale because it is a functional language, not in spite of being one. The functional paradigm, combined with Erlang’s actor model for concurrency, fit the requirements of fault-tolerant, scalable systems that must operate continuously without interruption.
Beyond Excel and Erlang: The Expanding Functional Ecosystem
The functional programming paradigm has expanded well beyond these two prominent examples:
WhatsApp and Chat Applications
WhatsApp, used by billions of people worldwide, was built using Erlang for its backend. The functional, concurrent nature of Erlang allowed WhatsApp to support millions of simultaneous connections with a small engineering team. Similarly, WeChat, China’s dominant messaging platform with over a billion users, relies on Erlang for handling massive concurrency.
Message Queues and Data Systems
RabbitMQ, a widely used message broker, is implemented in Erlang. CouchDB and Riak, popular NoSQL databases, also leverage Erlang’s functional architecture to provide distributed, fault-tolerant data storage. These systems form critical infrastructure for countless applications across all industries.
Elixir: Functional Programming for Web Development
Built on the Erlang virtual machine, Elixir has brought functional programming principles to web development through the Phoenix framework. As the Elixir website explains, the language and its ecosystem allow “developers to be productive in several domains, such as web development, embedded software, machine learning, data pipelines, and multimedia processing, across a wide range of industries.”
Functional Features in Mainstream Languages
Even traditionally imperative languages have increasingly adopted functional programming features:
- JavaScript has embraced functional patterns with arrow functions, map/reduce operations, and immutability libraries
- Python has incorporated functional programming constructs like list comprehensions and higher-order functions
- Java added lambda expressions and streams in Java 8
- C# has continuously expanded its functional programming capabilities by siphoning off examples from F#
Why Functional Programming Spread Without Notice
The way functional programming gained ground points to a few patterns in how adoption happens in technology:
1. Application Before Theory
Unlike object-oriented programming, which was heavily marketed as a paradigm, functional programming gained adoption through practical applications that solved real problems. Users of Excel don’t care about lambda calculus or referential transparency; they care about building useful tools for business decision-making. Surfacing aspects of theory followed the practical success, rather than preceding it.
2. Domain-Specific Embedding
Functional programming found success by embedding itself within domain-specific tools rather than asking developers to switch languages entirely. Excel users don’t think of themselves as functional programmers; they think of themselves as using Excel. This domain-specific embedding allowed functional concepts to spread without the resistance that comes with language switching.
3. Focus on End-User Benefits
The success of functional programming in tools like Excel comes from focusing on end-user benefits rather than programming philosophy. Spreadsheets make the functional paradigm’s benefits of data dependency tracking and automatic recalculation immediately tangible to users without requiring them to understand the underlying concepts.
The Future: From Hidden to Explicit
As functional programming continues to evolve, we’re seeing a trend toward making its presence more explicit while maintaining its accessibility:
- Microsoft’s addition of LAMBDA to Excel acknowledges and enhances its nature as a functional programming environment
- The popularity of Elixir demonstrates demand for accessible functional programming in web development
- F# aimed to bring functional-first programming to enterprise environments. Later it extended to the web via Fable. And now our Clef language reaches native applications and systems programming through our Fidelity framework.
- And even educational initiatives increasingly recognize Excel as a pathway to teaching programming concepts
The Paradigm Most Users Never Noticed
While computer science academia and professional developers debate programming paradigms, the one that reached the widest audience is the one that slipped into everyday use without most of its users realizing they were programming at all.
Excel brought functional programming to hundreds of millions of people who would never write a line of Haskell. Erlang connects phone calls and routes network traffic to its destination. Elixir runs websites in daily use. The paradigm has been in place across this infrastructure for decades, working underneath tools whose users never had to name it.
We see that lineage running straight into our own work. F# carried functional-first programming into enterprise and then to the web, and our Clef language now carries it into native and systems programming through our Fidelity framework, where we will keep building as the work continues.
References
“Advancing Excel as a programming language with Andy Gordon and Simon Peyton Jones.” Microsoft Research Podcast, July 19, 2021. https://www.microsoft.com/en-us/research/podcast/advancing-excel-as-a-programming-language-with-andy-gordon-and-simon-peyton-jones/
“Functional Programming Languages and the Pursuit of Laziness with Dr. Simon Peyton Jones.” Microsoft Research Podcast, May 23, 2018. https://www.microsoft.com/en-us/research/podcast/functional-programming-languages-pursuit-laziness-dr-simon-peyton-jones/
“Spreadsheets: Functional Programming for the Masses.” SlideShare, May 10, 2014. https://www.slideshare.net/kfrdbs/peyton-jones
“Excel: The Functional Programming Tool You Didn’t Know You Had.” The New Stack, February 8, 2022. https://thenewstack.io/excel-the-functional-programming-tool-you-didnt-know-you-had/
“Erlang (programming language).” Wikipedia. https://en.wikipedia.org/wiki/Erlang_(programming_language)
“Uses of Erlang in Telecom.” Stack Overflow. https://stackoverflow.com/questions/2474129/uses-of-erlang-in-telecom
“What is Erlang.” Erlang.org. https://www.erlang.org/faq/introduction.html
“Using Erlang for an Open Telecommunications Platform.” Methods & Tools. https://www.methodsandtools.com/archive/erlang.php
“The Elixir programming language.” Elixir-lang.org. https://elixir-lang.org/
“Beyond functional programming with Elixir and Erlang.” Dashbit Blog. https://dashbit.co/blog/beyond-functional-programming-with-elixir-and-erlang