The F# code is consistently shorter, easier to read, easier to refactor and contains far fewer bugs. As our data analysis tools have developed … we’ve become more productive.

  1. Kaggle
  2. permalink

At Kaggle we initially chose F# for our core data analysis algorithms because of its expressiveness. We’ve been so happy with the choice that we’ve found ourselves moving more and more of our application out of C# and into F#. The F# code is consistently shorter, easier to read, easier to refactor, and, because of the strong typing, contains far fewer bugs.

As our data analysis tools have developed, we’ve seen domain-specific constructs emerge very naturally; as our codebase gets larger, we become more productive.

The fact that F# targets the CLR was also critical - even though we have a large existing code base in C#, getting started with F# was an easy decision because we knew we could use new modules right away.

data science, machine learning, startup

 

The use of F# demonstrates a sweet spot for the language within enterprise software

  1. Simon Cousins
  2. source, permalink

I have written an application to balance the national power generation schedule for a portfolio of power stations to a trading position for an energy company. The client and server components were in C# but the calculation engine was written in F#.

The use of F# to address the complexity at the heart of this application clearly demonstrates a sweet spot for the language within enterprise software, namely algorithmically complex analysis of large data sets. My experience has been a very positive one.

energy, trading, calculations, ETL, extract, transform, load

 

At Credit Suisse, we’ve been using F# to develop quantitative models for financial products

  1. Howard Mansell
  2. Credit Suisse (at time of writing)
  3. source: CUFP Workshop, 2008, permalink

Building valuation models for derivative trades requires rapid development of mathematical models, made possible by composition of lower-level model components. We have found that F#, with the associated toolset, provides a unique combination of features that make it very well suited to this kind of development. In this talk, I will explain how we are using F# and show why it is a good match. I will also talk about the problems we have had, and outline future enhancements that would benefit this kind of work.

The abstract to a talk at the Commercial Users of Functional Programming workshop

financial services, analysis, fixed income, derivatives, financial modelling

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To add a new testimonial, log on to GitHub, edit this page and send the pull request. You can also send testimonials by email to fsharp@fsharp.org.

 

The performance is phenomenal. We can now re-calculate the entire bank portfolio from scratch in less than a second and the response-time for single deal verification calculation is far below 100 milliseconds.

  1. Jan Erik Ekelof, M.Sc.
  2. Head IT-architect and lead developer Counterparty Risk
  3. Handelsbanken
  4. permalink

I first evaluated F# back in 2006 - 2007 for the purpose of math oriented high performance applications within Financial Risk. I got in spring 2009 a mission to implement a new Real-time Counter-party Risk system covering all possible present and future deal types within the entire bank. The effort was started with only three resources, me as architect and lead developer and two colleagues – one risk expert and one high performing developer. Our first intention was to use C#, but I did a quick proof-of-concept with F# implementing a low level TCP/IP-communication to an existing risk-system. This showed us and our management that F# could give us a real productivity boost due to its support for multiple paradigms and functional concepts together with an impressive support for multi-threading.

Our first delivery is approaching rapidly and F# has proved itself as a real life-saver. We started off using C# in many places but have since then moved almost entirely into F# due to its ability to reduce the amount of code required and its simplicity when developing massive parallel computations. The performance is phenomenal. We can now re-calculate the entire bank portfolio from scratch in less than a second and the response-time for single deal verification calculation is far below 100 milliseconds(the original demand was 200 milliseconds to make the application usable for electronic markets). Although some gains are to be attributed to how we have built our calculation models, F# made it possible for us to implement our algorithms and techniques with very little code and with a huge similarity to the original mathematical models and regulations (which is important for verification of correctness). We have also been able to use the support for Async-workflows producing code that is simple and clear and easy to understand but still runs in parallel when required.

The present application contains 35 to 40.000 lines of F#-code and an equal amount of C#-code. However, our estimate is that the F# code contains at least 80% of the functionality (which is pretty amazing!). Our experience shows us that the number of code lines shrinks with a ratio of 1/2 to 1/4 by just porting functionality from C# to F# (not counting single character or empty lines in the C#-code). We have by remodeling increased the ratio to the area of 1/5 to 1/8, where the remodeling involves replacing object oriented constructs with functional ones (and actually removing mutable states). One example from last week was a limit-utilization module written in F# but using an object-oriented approach containing +300 lines of code. I rewrote it to below 70 lines of code just by shifting paradigm (and the rewrite made it much easier to understand and verify)!

financial services, analysis, counterparty risk, fixed income, derivatives, financial modelling

 

The benefits of functional programming in F# have given us a great advantage over our slow moving competitors.

  1. Bayard Rock
  2. permalink

At Bayard Rock we work hard every day in the pursuit of new approaches towards anti-money-laundering. Before adopting F# there were often months of turnaround time between development of an idea and actually testing it on real data in our production environment. F#’s succinctness and composability allows us to rapidly iterate on ideas while the type system acts as a safety net. On top of this, it has the advantage of being a first class member of the .NET ecosystem and so integrates seamlessly with our Microsoft stack systems. This means that instead of months we can often see our ideas come to life in just days.

The benefits of functional programming in F# have given us a great advantage over our slow moving competitors. After three years of using F# our products have consistently gotten significantly better each year without sacrificing stability. Our clients often are amazed by how we can quickly adapt to unique challenges and how we can find the bad guys hiding in their data much more effectively than anyone else. Little do they know that it’s largely thanks to our secret weapon, F#.

financial services, analysis, anti-money-laundering, counterparty risk, machine-learning

 

Grange Insurance parallelized its rating engine to take better advantage of multicore server hardware

  1. Grange Insurance
  2. permalink

For nearly 75 years, Grange Insurance has offered competitive products and services to policyholders in more than a dozen U.S. states. To maintain its well-earned reputation and standing, the company decided to enhance its rating engine—a software tool for rating policies and performing what-if modeling, impact analyses, and other vital activities. Working with the Sophic Group and using the Microsoft Visual Studio Team System development environment and F# programming language, Grange Insurance parallelized its rating engine to take better advantage of multicore server hardware, and in so doing garnered significant performance benefits. Processes that used to require hours now take just minutes, enabling the company to trim time-to-market by weeks and making it far easier for independent agents to sell and service Grange products.

insurance, parallelization, financial services

 

Large insurance company developed an entire pension quote calculator entirely in F# in under 100 days with no prior F# experience at all…

  1. Large insurance company
  2. source 1, source 2, source 3, permalink

One of the world’s largest insurance companies have F# code in production, are starting several more projects in F#. We are currently consulting for this company (£2.5bn profit) who have migrated some of their number crunching and business logic to F# and are so happy with the results (10x faster and 10x less code vs their Visual C++ 6) that they are proposing to migrate 1,600,000 lines of code to F#. In particular, their developers found F# easy to learn and use.

… my predecessor developed an entire pension quote calculator (typically scheduled to take 300-400 man days) entirely in F# in under 100 days with no prior F# experience at all. Performance is 10× better than the C++ that it replaces because the new code avoids unnecessary copying and exploits multicore parallelism. Part of my job here will be to give basic F# training to around 20 people and bring a few people up to expert level.

In answer to “Can you give any evidence for 10x performance gain over C++?”. The insurer’s C++ code is a simple manual translation from very inefficient Mathematica code that suffers from several pathological performance problems mainly centered around excessive copying. The F# rewrite does not have these problem. The 10x performance gain was verified by the client.

financial services, insurance, actuarial

 

Our risk and analytic capabilities (…) are entirely written in F#

  1. Lawrence Austen
  2. Chief Risk Officer at Trafigura
  3. source, permalink

…work directly with Trafigura’s Chief Risk Officer/Head of Quantitative Analysis, cranking code and rapidly extending our risk and analytic capabilities, which are entirely written in F#.

Trafigura Limited engages in the supply and offtake of crude oil, petroleum products, liquefied petroleum gas, metals, and metal ores and concentrates worldwide. Its solutions include trading, financing, hedging, and logistical support….

comodities, trading, risk, analysis

 

The F# solution offers us an order of magnitude increase in productivty…

  1. GameSys
  2. Yan Cui
  3. Lead Server Engineer
  4. source, permalink

F# is becoming an increasingly important part of our server side infrastructure that supports our mobile and web-based social games with millions of active users. F# first came to prominence in our technology stack in the implementation of the rules engine for our social slots games which by now serve over 700,000 unique players and 150,000,000 requests per day at peaks of several thousand requests per second. The F# solution offers us an order of magnitude increase in productivity and allows one developer to perform the work that are performed by a team of dedicated developers on an existing Java-based solution, and is critical in supporting our agile approach and bi-weekly release cycles.

The agent-based programming model offered by F#’s MailboxProcessor allows us to build thread-safe components with high-concurrency requirements effortlessly, without using locks and sacrificing maintainability and complexity. These agent-based solutions also offer much improved efficiency and latency whilst running at scale. Indeed our agent-based stateful server for our MMORPG has proved a big success and great cost saver that we’re in the process of rolling it out across all of our social games!

gaming, agents, cloud, big data, scalability

 

For a machine learning scientist, speed of experimentation is the critical factor to optimize.

  1. Patrice Simard
  2. Distinguished Engineer
  3. Microsoft
  4. permalink

I wrote the first prototype of the click prediction system deployed in Microsoft AdCenter in F# in a few days.

For a machine learning scientist, speed of experimentation is the critical factor to optimize. Compiling is fast but loading large amounts of data in memory takes a long time. With F#’s REPL, you only need to load the data once and you can then code and explore in the interactive environment. Unlike C# and C++, F# was designed for this mode of interaction. It has the ease of use of Matlab or Python, both of which I have used extensively in the past. One problem with Matlab and Python is that they are not strongly typed. No compile-time type checking hurts speed of experimentation because of bugs, lack of reusability, high cost of refactoring, no intellisense, and slow execution. Switching to F# was liberating and exhilarating. 2 caveats: Not every problem fits that model. With a bit of discipline, such as avoiding massive parallelism for as long as possible, the model goes a long way. The second caveat is that the cost of learning F# is steep. For me, it was 2 weeks of decreased productivity. It has proven a worthwhile investment.

As a machine learning practitioner programming in F#, I constantly switch between two activities: 1) writing prototype code (highly interactive ugly code with throw away results, functions, and visualizations) and 2) upgrading prototype code to library standard (fast, generic, reusable). When I go back to writing prototypes, I build on top of the newly upgraded functions. In F#, the cost of switching between these two modes is minimal: often nothing needs to be done other than adding comments and deleting deprecated functions.
This means that most of the time is dedicated to experimenting and the majority of the code is close to shipping quality. Some people can do this in C# or Matlab, but I find that F# excels at it.

I started F# with deep suspicions regarding efficiency. My first test was to link F# with C++/CLI and check performance of calling SSE/AVX optimized code. As hoped, F# is comparable to C# when it comes to speed. You have the same flexibility to link with well optimized code. The inline generics are truly magical: same IL in the linked DLLs, but the functions expand to specialized fast code when you instantiate them. Compromises between intuitive code and efficient code still need to be made. I found that “for” loop, “tail recursive” loop, or Parallel.For with ThreadLocal loops, are faster than a succession of piped IEnumerables (seq in F#). F# does not hamper one’s ability to write ugly fast code. Rest assured.

Several people in the machine learning group in Microsoft Research have switched to F# for the reasons above. The world is slowly moving toward functional programming with good justifications: the code is cleaner and easier to debug in a distributed environment. Among the available functional languages, F# is a compelling option.

advertising, machine learning, data science, statistics, predication

 

We see great potential for F# to be used as scripting languages in CAD, it fits very well for computational design challenges in the construction industry.

  1. Goswin Rothenthal
  2. Design Engineer
  3. Waagner Biro
  4. permalink

In recent years many Architects have discovered that they can greatly enlarge their design repertoire by the use of parametric design, programming or scripting. Architects can now quickly and easily explore new geometries previously unseen in Architecture. Besides being designed in a novel way these geometries can also be exactly represented and reasoned about in terms of structural feasibility and manufacturing constraints. These facts take new geometries out of the dreams of Architects and make them real candidates for construction.

One such project is the Louvre Abu Dhabi by Jean Nouvel. Waagner-Biro was awarded the construction contract for the Dome. For the cladding of this dome more than 450´000 individual cutting and drilling patterns of custom aluminium extrusions had to be described and automated. The shear scale and complexity of the cladding on the dome required us to re-evaluate our parametric design approach. I developed a F# application to represent and organize all cladding elements of the dome. It includes a small geometry kernel and an adapted version of the Half Edge Data Structure to efficiently query the neighbourhood of each element. I used [Rhino] (http://www.rhino3d.com/) and its .NET API to host the F# DLL for drawing and visualisation. This application enabled us to have an integrated workflow from the main geometry setout all the way done to the manufacturing data in a single parametric model. This project was the first use of F# at Waagner-Biro for a large scale project. The switch to F# from dynamic scripting languages helped to reduce development time and runtime. The strongly typed environment, algebraic data types and immutable data helped to avoid a whole range of bugs and fits well the domain of generating static 3d geometry. I see great potential for F# to be used as scripting languages in CAD, especially since most big CAD packages do already offer a .NET API.

(Image credits: Jean Nouvel Architects)

geometry, CAD, construction industry, Rhino

 

The results speak for themselves.

  1. Matt Ball
  2. Liz Earle Beauty Co. Ltd
  3. source, permalink

As a business we actively seek improvement every single day. This is the same for our IT systems, so we have been searching for a means to do that in our in-house software systems.

The F# type system has allowed us to do this - by eliminating null references, increasing type safety and creating rich domain models that help us express hard-and-fast business rules in a way that we can really lean on the compiler; while actually reducing our total lines of code (and noise!). Doing so has reduced both our requirement for expensive bug hunts in our production systems, and the overall cost of maintaining unnecessary code complexity.

We have been evaluating F# for a year now, and have components in our production systems that have been bug-free since deployment. The results speak for themselves.

retail, e-commerce, ETL, web services, soa, correctness

 

…we have decided to use F# as our functional language to have automatic integration with rest of the system…

  1. EMEA-based Security Solutions Company
  2. permalink

We develop security product to protect critical infrastructure (e.g. Oil Refinery, Airport, etc) for countries across the globe…. In core of our product there are prediction algorithms. We use different modeling and theorems (Monte Carlo, Action, etc) to implement the prediction components. … Since we are rewriting our next generation product using .NET, we have decided to use F# as functional language to have automatic integration with rest of the system. … We also have advanced machine learning components (Artificial Intelligence) and functional languages are the best fit to write AI stuff. We are planning to use F# as the primary programming language in this area because of its interoperability with .NET.

security, integration

 

With its new tools, the bank can speed development by 50 percent or more, improve quality, and reduce costs.

  1. Large Financial Services Firm, Europe
  2. source, permalink

A large financial services firm in Europe sought new development tools that could cut costs, boost productivity, and improve the quality of its mathematical models. To address its needs, the bank deployed F#, the .NET Framework, and Visual Studio. It will soon upgrade to Visual Studio 2010 and then integrated F#. With its new tools, the bank can speed development by 50 percent or more, improve quality, and reduce costs.

financial services, financial modelling, derivatives, fixed income

 

F# encourages Reason Driven Development that leads to virtually bug-free code

  1. Boston-based Financial Services Firm, Fixed Income
  2. permalink

We are using F# because it considerably increases speed of software development which is crucial for a small company with limited development resources. The most enjoyable feature of this language is that the developer can reason about the code instead of relying only on unit tests. I would say the language encourages Reason Driven Development methodology which leads to virtually bug-free code. F# as strongly typed functional language ideally fits for tasks our software solves – Fixed Income securities trading optimization. It is also very important that F# computation engine could be seamlessly integrated with other parts of .NET-based software product.

fixed income, trading, optimization, financial services

 

At a major Investment Bank, we used F# to build an Early Warning Indicator System for Liquidity Risk

  1. Stephen Channell
  2. Cepheis Ltd
  3. Case Study, permalink

Early Warning Indicators is a standalone dashboard application to monitor real-time market movements and highlight potential risk for further analysis. EWI subscribed to real-time equity, Forex and commodity prices and needed to calculate Red/Amber/Green status in real-time for tolerance breaches and to generate dashboard reports as needed.

The business wanted the flexibility to define formulas using Excel expressions, but spreadsheet components could not cope with the data-rate without conflation and management didn’t want a solution that relied on an Excel template and IT change control to add new indicators.

F# was chosen for development productivity, performance of a cell framework implemented using computation expressions; ease with which Excel expressions could be parsed as a DSL and .NET integration with QALib, Market and timer-series data.

Post implementation review highlighted that (given resource and time constraints) functionality would have been sacrificed without F# and its associated tooling.

 


I keep being surprised by how compact and readable F# is…

  1. London-Based Asset Management Company
  2. permalink

We have set up a complete risk management system that combines several data sources, presents them in a … WPF user interface, and does a LOT of calculation behind the scenes. When the calculation requires a proper algorithm (i.e. anything that is more complex than a simple for loop), our choice has been F#. I have to say I keep being surprised by how compact it is and, nonetheless, how readable it is even when I’m reading code that I hadn’t looked at or thought about for six months.

data, analysis, calculation, financial services, derivatives

 

The efficient use of functional programming throughout the R&D cycle helped make the cycle faster and more efficient.

  1. Moody Hadi (CME Group)
  2. source, permalink

The credit markets have varying pockets of liquidity. Market participants would like to understand how the liquidity of their set of entities changes relative to the overall market. A liquidity scoring model is needed to provide these metrics across the entire CDS universe. Functional programming and specifically F# was used in order to provide the market with a fast and accurate solution. … The research and development cycle was made faster and more efficient by the effective use of functional programming.

The efficient use of functional programming throughout the R&D cycle helped make the cycle faster and more efficient. Less time was spent on translating requirements, miscommunications etc and more on producing a fast and accurate solution quickly.

Since programmers can understand your quant code they can focus on their core competency – developing fast and reliable production code. The development exercise becomes catered towards optimization, performance tuning and error handling (i.e. making the code reliable) Functionality is not lost from the prototype due to miscommunication or rather crude documentation/requirements, which saves time in testing. Mass regression testing is easy with precise precision level differences between the prototype and the production system.

 

F# allows you to move smoothly in your programming style

  1. Julien Laugel, eurostocks.com
  2. source, permalink

I’ve been coding in F# lately, for a production task. F# allows you to move smoothly in your programming style… I start with pure functional code, shift slightly towards an object-oriented style, and in production code, I sometimes have to do some imperative programming. I can start with a pure idea, and still finish my project with realistic code. You’re never disappointed in any phase of the project!

imperative, functional, financial services, portfolio analysis

 

I have now delivered three business critical projects written in F#. I am still waiting for the first bug to come in.

  1. UK-based Power Company
  2. Simon Cousins
  3. source, permalink

I am both a C# dev and an F# dev. I can only offer subjective anecdotal evidence based on my experience of delivering projects in both languages (I am too busy delivering software to do anything else).

That said, the one stat in the summary that I find most compelling is the defect rate. I have now delivered three business critical projects written in F#. I am still waiting for the first bug to come in. This is not the case with the C# projects I have delivered. I will continue to monitor and report on this. It might be that I am just on a lucky streak, but I suspect that the clarity and concision of F# code contributes greatly to its correctness.

energy, extract, transform, load, ETL

 

F# proved ideal for the complex data machinations required to build the models from raw Excel input.

  1. A Fortune 100 Manufacturer
  2. Supplied to FSSF, permalink

We developed a ClickOnce F# / WPF application that scores and ranks thousands of models of part-supplier combinations using Microsoft Solver Foundation (MSF). Agents can chose from the highest scoring combinations to optimize purchasing decisions. F# proved ideal for the complex data machinations required to build the models from raw Excel input. Also, the MSF supplied F# functional wrapper is a great way of using Solver Foundation from F#.

manufacturing, optimization, Excel, solver

Around 95% of the code in these projects has been developed in F#

  1. Anton Schwaighofer, Microsoft
  2. bing Ads Ranking Allocation and Pricing
  3. source, permalink

Around 95% of the code in these projects has been developed in F#. F# allowed for rapid development of prototypes, and thus also rapid verification or falsification of the underlying mathematical models. Complex algorithms, for example to compute Nash equilibria in game theory, can be expressed succinctly. Units of measure reduced the chance of errors dramatically: Prices, probabilities, derivatives, etc. can already be kept apart at compile time.

advertising, ranking, rating, machine learning, statistics

 

F# is central to Microsoft’s quantum algorithm research

  1. Dave Wecker
  2. Microsoft Advanced Strategies and Research
  3. permalink

F# is central to Microsoft’s quantum algorithm research. The LIQUi|⟩ simulator (Language Integrated Quantum Operations) presents an extension of F# that presents a seamless integration of classical and quantum operations. The scale and efficiency of the simulator allows it to handle among the largest entangled systems of qubits (quantum bits) ever modeled utilizing a targeted linear algebra package written entirely in F#. In addition, the modular architecture allows users to easily extend the system in any desired research direction. The base library is well over 20,000 lines of code and implements a wide range of modules including circuits, molecular modeling, spin-glass systems, quantum error correction, machine learning, factoring and many others. The system runs in client, server and cloud environments. It is also designed to be used as an educational tool and we have found that bringing new users up to speed is a quick and painless process.

simulation, quantum, Microsoft, modelling

 

F# is the night vision goggles I need when I go into the dark and attempt to solve previously unsolved problems.

  1. Professor Byron Cook
  2. Microsoft, permalink

I’m one of the first users of F#, since 2004. In my work (e.g. SLAM, Terminator, Zapato, T2, etc) I find that F# is the night vision goggles I need when I go into the dark and attempt to solve previously unsolved problems. Everything becomes simple and clear when expressed in F#.

verification, algorithms, analysis, problem solving

 

F# will continue to be our language of choice for scientific computing.

  1. Dr. Andrew Phillips
  2. Head of Bio Computation Group
  3. Microsoft Research, permalink

I lead the Biological Computation group at Microsoft Research, where we are developing methods and software for modelling and analysis of biological systems. We have been using F# in our group for the past 7 years, and it’s the language of choice for all of our software development. In particular it forms the basis of our software for programming computational circuits made of DNA, for programming genetic devices that operate inside cells, and for programming complex biological processes in a modular way.

The functional data structures and static type-checking that F# provides are ideally suited for developing these domain-specific languages, and the Visual Studio integration is superb for debugging and source control. The integration with .Net is seamless, and allows us to incorporate efficient numerical and visualisation libraries written in C#. It also allows us to take advantage of the full suite of .Net UI components.

Our languages are specified with a formal syntax and semantics, which are rigorously analysed prior to their implementation. Programming in a functional language like F# brings the implementation much closer to the formal specification, which is important for ensuring accurate simulation and probabilistic analysis. Correct implementation of the semantics is critical, since even small coding errors can give rise to divergent predictions, which can in turn compromise biological experiments. F# is a great language for writing clean, concise code, which is statically typed within a professional development environment that supports a wealth of libraries. It will continue to be our language of choice for scientific computing.

biology, modelling, algorithms, analysis, DNA computing, correct, scientific computing

 

In our engineering group at Microsoft we use F# for several projects

  1. Microsoft Engineering Team
  2. permalink

In our internal engineering group at Microsoft, F# is used for several important tools: * analyzing feedback on the web to look for compatibility-related issues, * a static code analyzer to detect compatibility regressions in a product, * a delta-debugging tool to help root cause regression analysis in product builds.

tools, engineering, debugging, builds, static analysis

 

The simple, well-designed and powerful core of the language was perfect for introducing the fundamental concepts of functional programming.

  1. Michael R. Hansen
  2. Associate Professor, Technical University of Denmark
  3. permalink

Producing an F#-based book on functional programming has been a fantastic experience.

Using this material in an F#-based course introducing the fundamental concepts of functional programming has been a delightful experience as well. The simple, well-designed, yet powerful, core of the language was perfect for that purpose and, to our surprise, the transition from using SML to using F# actually made the tooling easier for students no matter which platforms they used.

Furthermore, F# with it rich runtime environment has proved to be an excellent programming platform in research applications and in a more advanced course aiming at showing the role of functional programming in a broad variety of applications ranging from computer science applications to more real-life applications. In the first version of this course, given together with Anh-Dung Phan, the students completed three projects in three weeks: One being an interpreter for a rich imperative programming language, another being implementation, application and analysis of a functional pearl, and the last being a curriculum planning system for studies at the Technical University of Denmark.

 

Solving a number of programming problems using the language convinced me of the supreme qualities of F#

  1. Hans Rischel
  2. Former teacher of computer science at the Technical University of Denmark
  3. permalink

I was approached by my former colleague Michael (Michael R. Hansen) in autumn 2010 where he proposed that we should write a new textbook on functional programming - now using the F# programming language. To begin with I was quite sceptical about using a programming language appearing as part of a Microsoft program package. Solving a number of programming problems using the language convinced me, however, of the supreme qualities of F# - and we embarked on the project of getting acquainted with F# and writing the textbook.

Michael and I spent considerable time solving traditional programming problems in F#. A combination of functional and imperative F# with an occasional pinch of OO gives a very pleasing platform for program development - once you have found your way through the wilderness of MSDN documentation (newcomers to the MSDN world may benefit from the keyword index to the MSDN library documentation found on the web-site of the book). All of Chapter 10 and part of Chapter 11 present program examples using this programming style.

Computation expressions look esoteric to begin with, but they are actually rather useful. We spent much time trying to get this concept down to earth, with the purpose of making it accessible to simple-minded people like ourselves. The reader may judge how far we succeeded by studying Chapter 12 of the book.

Writing this textbook with Michael has been an exciting experience.

 

F#’s powerful type inference means less typing, more thinking

  1. Don Syme
  2. Principal Researcher, Microsoft
  3. Eclipse Summit Europe 2009, source, slide 49
  4. permalink

F# was used on Microsoft’s AdPredict project for adCenter. This was a 4 week project with 4 machine learning experts involving a model with 100million probabilistic variables and processing 6TB of training data in real-time. 2 weeks of CPU time were used during training. Benefits included Quick Coding - F#’s powerful type inference means less typing, more thinking, Agile Coding - Type-inferred code is easily refactored, Scripting - “Hands-on” exploration, Performance - Immediate scaling to massive data sets, Memory-Faithful - Mega-data structures on 16GB machines, Succinctness - Live in the domain, not the language, Symbolic - Schema compilation and “Schedules” and .NET Integration - Especially Excel, SQL Server

integration, machine learning, advertising, prediction

 

…The AI is implemented in F#…

  1. Microsoft, Path of Go
  2. video source, permalink

Path of Go is powered by three technologies…: an AI capable of playing Go, the F# language, and TrueSkill to match online players. The AI is implemented in F# and meets the challenge of running efficiently in the .net compact framework on Xbox 360. This game places you in a number of visually stunning 3D scenes. It was fully developed in managed code using the XNA environment.

artificial intelligence, statistics, machine learning, TrueSkill

 

…the core logic is written in F# wherever possible…

  1. Andrea D’Intino
  2. Yellow blue soft
  3. permalink

Yellow blue soft is a truly international Micro-ISV: We are a small, dynamic and international team who is wondering why file-management is lagging 30 years behind and no one seems to care or even notice. We do. We love what we’re doing and most importantly we love listening to you! Visit our blog to know more about us and join our forum to become part of our sparkling community.

The tabbles are special containers that you can use to categorize any kind of file and document as well as folders and bookmarks. Using Tabbles you can quickly categorize, find, sort and share your documents, in a totally new way.

applications, business logic

 

When F# is combined with Visual Studio… productivity goes through the roof!

  1. Prof Nigel Horspool
  2. University of Victoria, Canada
  3. source, permalink

F# programs tend to be much shorter than their equivalents in other languages. The fewer lines of code required, of course, the higher the productivity. When F# is combined with Visual Studio, which provides help with remembering the methods attached to different data types and how to use those methods, productivity goes through the roof!

teaching, research

 

…That’s the reason we have chosen F# for our undergraduate functional programming class…

  1. Prof. Peter Sestoft
  2. IT University of Copenhagen
  3. permalink

F# has a beautiful, simple but expressive language at its core, and many powerful features built around that core language. It can draw on all the power of the .NET libraries, and runs on Windows, MacOS and Linux. That’s the reason we have chosen F# for our undergraduate functional programming class as well as our undergraduate programming language class (link)

teching, research, cross-platform

 

F#…levels the playing field between beginners and experienced programmers.

  1. Prof. Susan Eisenbach
  2. Imperial College, United Kingdom
  3. source, permalink

Functional languages are ideal for teaching clear thinking, for solving problems amenable to code solutions and it levels the playing field between beginners and experienced programmers. The first programming language taught has a substantial influence on what language students use when they have a free choice. F#, once it is platform independent, has the potential to become the first programming language.

teaching, research, cross-platform

 

F#…made it trivial…

  1. Prof David Walker
  2. Princeton University
  3. source, permalink

Our graduate course on Parallelism this Fall is full, even though it assumes no experience with functional programming or F#. The students are preparing the courseware themselves, and one of the topics we are studying is functional reactive programming (FRP) with continuous, time-varying behaviors. F#, with its rich graphics libraries, made it trivial to construct a super-fun assignment involving purely functional and interactive animation of a mock solar system.

teaching, research, cross-platform

 

We recommend teaching F# because it is an extraordinary and flexible tool for teaching different areas of Computer Science

  1. Antonio Cisternino
  2. University of Pisa, Italy
  3. permalink

At the University of Pisa we use F# for teaching UI programming, a fundamental course in the third year curriculum. In 2014 two more courses (Programming I & II) will use F# and Try F#.

We use F# for teaching because it fits teaching both fundamentals and technology thanks to rich programming environment and libraries to access all system resources (such as UIs). Moreover, F# feels like a dynamic language thanks to F# interactive even if it is a statically typed language. Our students use F# on Windows, Mac and Linux. Try F# is a particularly valuable tool for teaching because it has a quite sophisticated editor with interactive evaluation and the ability of sharing saved files with students.

I’ve also used F# for teaching programming for scientists at Scuola Normale Superiore, a PhD course at ITU Copenhagen and to graduate students in biomedical engineering.

We recommend teaching F# because it is an extraordinary and flexible tool for teaching different areas of Computer Science. The language is rich and its functional nature allows to easily define the appropriate subset for teaching particular concepts. I use it to teach entire classes by typing code and evaluate interactively discussing the results of a single evaluation. It is also a great tool for teaching programming to scientists and engineers: I found that its mathematical roots in lambda calculus are more readily grasped by non-programmers, and interactive evaluation recalls environments such as Matlab and Mathematica very popular in these communities.

 

F# is very popular among my students for the programming projects

  1. Simão Sousa
  2. University of Beira Interior, Portugal
  3. permalink

I teach and use OCaml and F# in my lectures (Theory of Computation, Formal Languages and Compiler Design, Formal Methods, Applied Cryptography), and F# is very popular among my students for the programming projects. Most of the students that are supervised by me (undergraduate, master but also PhD) use F# as the underlying programming language. This is even more the case now since part of our research directions includes working on cloud/distributed systems.

F# and its programming environment leverage with no doubt the ability and the productivity of my students. This is, in my opinion, for two main reasons. First, F# allows the student, but also the researcher like me, to focus on the key aspects of his creation, while, secondly, enhancing
technologically the work done in a so remarkable and facilitated way. Once drawn in paper and pencil, an algorithm is naturally implemented in F# and easily deployed in whatever is its execution context.

I am definitively a strong believer of F# and amazed by the language and its community.

teaching, research, cross-platform

 

I evaluated F# and it and found that for certain tasks it was better than C# in terms of performance while maintaining suitable readability

  1. Atalasoft
  2. source, permalink

I evaluated F# and it and found that for certain tasks it was better than C# in terms of performance while maintaining suitable readability and for certain tasks, it leant itself better to certain algorithms (OctTree based color quantization stands out). …we were able to heavily leverage inline functions in F#……Since each of these are inlines, the F# optimizer can actually do something useful with the code. By using F#, we were able to address this cost by using inlining, code profiling, scanline caching, memoization and other techniques. In many cases we ended up with code that ran in equivalent time to C++ code or in some cases faster.

algorithms, performance, immage processing

 

We would recommend F# as an additional tool in the kit of any company building software on the .NET stack.

  1. Michael Newton, Senior Developer
  2. 15below Ltd, permalink

Historically, our code base has been written in a mix of C# and VB.net. F#’s excellent interoperability with the rest of .NET allows us to use it for components where it’s particular strength’s shine without having to discard or rewrite our existing code.

Whether it’s driving the build and continuous integration system (due to scripting being a first class citizen in the F# world) or writing rock solid infrastructure components (due to the easy use of functional paradigms via features such as computational expressions, type inference and discriminated unions) we have found our F# code to be concise, easy to write and reliable to use. It is a perfect fit for many components within our messaging based architecture.

We would recommend it as an additional tool in the kit of any company building software on the .NET stack.

 

This software provides the user with maximum flexibility to move quickly through multiple images

  1. Forensic Software
  2. permalink

Forensic Comparison Software is the ideal tool for displaying two digital images, side by side, for comparison purposes. This software provides the user with maximum flexibility to move quickly through multiple images, in a manner that replaces the intensive manual comparison of hard copy photographs. Focusing on the individual’s needs, Forensic Comparison Software provides many intuitive and easy to use features for enhancing digital images.

security, algorithms

 

Bohdan … shows F#’s use for performing aggregations over large datasets, taking advantage of cpu and io parallelism

  1. Bohdan Szymanik
  2. source, permalink

Bohdan Szymanik, CTO at Kiwibank, is keen to show how he’s been using F# for analysis tasks within the bank. He’ll provide an intro to the language then show its use for performing aggregations over large datasets, taking advantage of cpu and io parallelism, and data presentation through charting and image generation.

financial services, data, analysis

 

I am using F# to develop an API for data encryption using fully homomorphic encryption.

  1. Vitor Pereira
  2. permalink

I am currently using F# to develop my undergraduate final project. The project consists in developing an Application Programming Interface that allows one to encrypt data using fully homomorphic encryption and I found in F# the ideal programming language to develop it.

Besides all the benefits of the functional paradigm for this type of work, F# interoperability with the .NET platform allows the construction of powerful implementations that other functional languages do not allow so easily.

I really hope that, in the future, I keep working in Cryptography using F# as the main programming language for my projects. I am also preparing a hands-on presentation about F# and Cryptography to be presented at an event in Microsoft Portugal, which I will surely enjoy!

security, cryptography, student, academia

 

I can tell you, F# really saved us a ton of effort.

  1. Giuseppe Maggiore
  2. permalink, source

I am the lead developer of Galaxy Wars, and I can tell you, F# really saved us a ton of effort. Monadic coroutines alone I believe are the reason why we manage to ship the thing on time…

games

 

I am using F# to develop an API for data encryption using fully homomorphic encryption.

  1. namigop (Erik Araojo)
  2. permalink, source

I’ve written two commercial apps in F#, WcfStorm.Rest and WcfStorm.Server.
The UI part was in C# and the library part was in F#. In my experience it is fun language to code in.

security, cryptography, student, academia

 

everyone gets really amazed when they try F# and experience its imense expressive power

  1. Mário Pereira
  2. Microsoft Student Partner (MSP)
  3. Faculty of Sciences, University of Oporto
  4. permalink

I have been a Microsoft Student Partner (MSP) for three years, which offered me the opportunity to be in touch with most portuguese faculties and their students, getting the change to be a bit of an evangelist for Microsoft technologies. I chose to spent my MSP experience giving introductory seminars to F# and functional programming using F#. So far, I have given these presentations on most portuguese faculties and also at Microsoft portuguese headquarters. The result is always the same: everyone gets really amazed when they try F# and experience its imense expressive power, its delightful syntax and realize they can do functional programming (which is oftenly taken as something boring and complicated) on a familiar and confortable environment. Currently, along with a fellow portuguese MSP, (following the success of previous presentations and in response to the many requests for new sessions on F#) I’m preparing an hands-on session on the use of F# for Cryptography, to be presented on a future event at Microsoft Portugal.

Personally, F# offers me a solid and trustable ground to develop reliable and complex applications on a confortable and succinct way, impossible to achieve with other languages and paradigms. With no doubt, I can say I’m a huge fan of F# and I’m always eager to get in touch with every new feature the language has to offer.

 

…your code is less error-prone…

  1. Dario
  2. source, permalink

You can formulate many problems much easier, closer to their definition and more concise in a functional programming language like F# and your code is less error-prone (immutability, more powerful type system, intuitive recurive algorithms). You can code what you mean instead of what the computer wants you to say ;-) Furthermore you can have F# and C# together in one solution, so you can combine the benefits of both languages and use them where they’re needed.

domain modeling, immutability

 

I’d recommend F#… learning another language is one way to become a better programmer.

  1. Antonio Hayley
  2. source, permalink

I’d recommend F# to a die hard C# developer just because learning another language is one way a programmer can get out of a local maxima and become a better programmer. And F# isn’t just a different set of semantics on top of the same syntax as most imperative languages are, it’s a totally different programming style. All the more to expand the capabilities and understanding of a programmer.

learning, imperative, functional

 

…We use F# in oceanographic research to connect multiple visualizations together in time and space…

  1. Rob Fatland, Microsoft Research
  2. permalink

We use F# in oceanographic research to connect multiple visualizations together in time and space, which is map-plane location and depth. We began by building our Narwhal Developers Library for Layerscape in C# with emphasis on visualizing flow lines and understanding drift experiment data. These data are quite complex, involving physical ocean state and measurement of microbial metabolic processes, consolidating remote sensing and passive drifters, and adding to all this current measurements with the tracks of autonomous robots. Our technical term for the visualization challenge is ‘horrible’.

To cope with the horrible we began adding F# scripts; and this has been extremely productive, particularly in morphing ideas about data exploration into real tools quickly. Our most interesting achievement to date is to wire a chart into a 4D visual environment. The set-up is like this: The scientist sees two views of the data: First color coded structure in a curtain plot of time versus depth (chlorophyll coded as color for example), and second this same data time-boxed in the dynamic Worldwide Telescope (WWT) visualization engine. F# is used to wire them together: Left click (and drag) in the chart to scroll the WWT clock back and forth. Right-click + drag in the chart to select a subset of the data which is then used to construct a new (small) advection visualization. Because the selected pieces are small and chosen interactively we get around the horrible problem of seeing everything at once. It is like seeing an entire forest and making all but a few curious trees vanish. So F# has been a great way to make rapid progress, and fun to learn as well.

visualiztion; astronomy; oceanographic research; Microsoft

 

…I have to say I love the language…

  1. Jared Parsons
  2. source, permalink

Over the last 6 or so months, I’ve been working on a Vim emulation layer. This is the first major project I’ve ever done with F# and I have to say I love the language. In many ways I used this project as a method of learning F# (and this learning curve is very much evident if you look through the history of the project). What I find the most amazing about F# is just how concise of a language it is. The Vim engine comprises the bulk of the logic yet it only comprises 30% of the overall code base.

learning, conciseness

 

There is a noticeable interest in the developer community in Russia towards F#.

  1. Dmitry Soshnikov
  2. Associate Professor, Moscow Aviation Technical University
  3. permalink

I do some samples in F# for the lectures and the book, but all that is within a single-user VS 2010 Pro installation. Right now we have a set of slides on functional programming with F# in Russian in the curriculum repository, and the video-course of functional programming using F# available in the largest Russian Internet-University (intuit.ru). The course is being taught in 2 universities. There is a noticeable interest in the developer community in Russia towards F#.

 

F# rocks… building out various algorithms for DNA processing here and it’s like a drug

  1. Darren Platt
  2. Amyris Biotechnology
  3. source, permalink

With F#… we have written a complete genome re-sequencing pipeline with interface, algorithms, reporting in ~5K lines and it has been incredibly reliable, fast and easy to maintain.

F# rocks - we’re building out various algorithms for DNA processing here and it’s like a drug. Just implemented a suffix tree in 150 lines that can index 200,000 bases a second ;) We have probably 10-20K lines of code for many scientific applications ranging from a full genome sequencing pipeline that reconstructs and annotated yeast strains, to simulators for various processes and design tools for building DNA sequences/constructs. There are lab located apps that grab robot log files and move them to databases and a tool for viewing a huge collection of DNA sequencing data.

F# has been phenomenally useful. I would be writing a lot of this in Python otherwise and F# is more robust, 20x - 100x faster to run and for anything but the most trivial programs, faster to develop.

The UI work is especially gratifying, because state of the art for a lot of genomic data display is still PNG images embedded in JavaScript and with F# I can render half a million data points on a web page without jumping through hoops.

With Units of Measure I started labelling the coordinates as one or zero based and immediately found a bug where I’d casually mixed the two systems. Yay F#!

biotechnology, units of measure, bioinformatics

 

Many attributes of the F# programming language make it an ideal choice for …the exponentially growing volumes of molecular analysis data

  1. Dr. Robert Boissy
  2. Assistant Professor
  3. University of Nebraska Medical Center
  4. permalink

I am involved in bioinformatics and computational genomics as a faculty member at the University of Nebraska Medical Center (UNMC). In an academic medical center like UNMC there are heavy demands on my time and a wide range of different types of research projects that I can end up working on. I have used the F# programming language on both the .NET and Mono frameworks for several of these projects, including one that involved a very productive collaboration with IntelliFactory and the use of WebSharper (http://www.websharper.com/home).
You can visit the resulting web site and read the freely available peer-reviewed scientific publication that describes the important infectious disease research that this F# software development project facilitates. I am always interested in opportunities to work with professional software development enterprises whose teams include developers with F# expertise, because I believe that many attributes of the F# programming language make it an ideal choice for the development of software solutions that integrate Electronic Health Record (EHR) data and the exponentially growing volumes of molecular analysis data that can now be obtained from individual patients (e.g., personal genome DNA sequencing data).

There’s an exciting future for F# in this huge, emerging, data-rich health care market.

bioinformatics, genomics, health, molecular analysis, simulation

 

F# makes is easy to spend your time answering interesting questions about the domain and less time answering questions about the language.

  1. Jamie Dixon
  2. Coder
  3. Cary, North Carolina
  4. permalink

I did a public records request in my town of Cary, North Carolina. The dataset included appx 25,000 traffic stop records for 2012. Using F#, I did some basic statistical calculations to determine that when you are driving is much more important than where you are driving in terms of getting stopped. In fact, the term ‘speed trap’ is a misnomer. In addition, the data supports the notion that there is a monthly quota of tickets being given. You can read the entire analysis here

Also, I created a KNN classifier using the date/time of the stop and determined that when you get stopped impacts weather you get a verbal warning versus an actual ticket. You can read the entire analysis here

Finally, I did a public records request in the county in which I live: Wake County North Carolina. The dataset included appx 5,000 health inspection scores for 2012. Using F#, I did some basic statistical calculations to determine that there is little variance of when a restaurant gets inspected and their final score. An interesting offshoot is that some particular restaurants scored lower across all inspectors - except when head inspector did the inspection, then they actually scored better. There might an inherent cultural bias by the inspectors. You can read the entire analysis here

F# was great because I spent less time figuring out how to answer my question and more time actually answering the question. The type providers made consuming and integrating hetrogenous datasets a snap and the pattern matching feature reduced the complexity of the code by an order of magnitude (compared to C#). Finally, by using unit tests and immutable data types, I have a bug-resistant code base that can be extended to other scenarios.

analytics, open data

 

The power and flexibility of the language lets us ship features faster, with fewer bugs.

  1. Marty Dill
  2. Reminder Hero
  3. permalink

All of our back-end data processing and parsing is done in F#. The power and flexibility of the language lets us ship features faster, with fewer bugs. Regressions are virtually nonexistent, and the functional nature of the language makes it easy to ensure that our code is testable.

Our first iterations were written in C#, but after switching to F#, we saw a drastic reduction in code size, along with an increase in readability. We’ll definitely be sticking with F# for all of our future projects.

data, parsing, processing, readability

 

With F# I can develop libraries in a fraction of the time.

  1. Mauricio Scheffer
  2. permalink

I’ve been using F# libraries in otherwise mostly C# / VB.NET web applications. Thanks to the conciseness of F#, I can develop these libraries in a fraction of the time, then I consume them from C# and VB.NET just like any other library.

Furthermore, F#’s succint syntax and REPL make it an excellent scripting language and good for data exploration. Thanks to F#’s interoperability the scripts can easily use domains and libraries written in C#. You never need to start from scratch or have to reinvent things.

Language features like record types, discriminated unions and type inference also make F# a great language for prototyping. I often prototype new business domains in F# with a few simplified use cases to refine it. The simple syntax allows me to focus on developing the domain and iterate more quickly. Then, when company policy requires it, I translate it to C# which is usually a straightforward process that ends up with many times more lines of code (yet still perfectly maintainable).

web, domain modelling

 

F# is a powerful language and it is great to do cross platform development with it.

  1. Can Erten
  2. Codingday
  3. Vector Code
  4. permalink

Vector code is a code generator for iOS and OsX generating code in Objective C, Swift and C#. It works with vector graphics, parses and runs SVG. It is developed with F# on a Mac.

F# is a first class language for Mac OsX. Thanks to the open source compiler, mono and xamarin, I was able to build a vector drawing, code generator software with F#. It is really amazing experience! The tooling is great and keeps improving. The compiler and the language are basically the same which is fantastic!

F# is a powerful language and it is great to do cross platform development with it. I used heavily quotations for generating code in different languages on vector code. Powerful type system and static compilation meant that, once the application compiled without errors and warnings, it will just work and generate complete code. It did, and now at the App Store.

osx, mac, code generation, cross-platform

Additional Case Studies

The following written or recorded case studies describe the benefits of F# for a range of enterprise scenarios: