Rick Minerich's Development Wonderland : math

F# Discoveries This Week 09/17/2010

RickM — Fri, 17 Sep 2010 20:25:06 GMT

ICFP approaches quickly and I’m working hard to make that those four hours of CUFP F# tutorial will be well worth your time. Meanwhile I’ve gathered the best the of the F# community for your enjoyment. Dig in!

News

September 23rd at CUFPx Michigan - Mark Harris: "A Commercial Deployment of F# "

“Mark Harris, formerly of Microsoft, currently working for Grange Insurance in Columbus, Ohio, will be presenting a case study of a commercial deployment of an F# solution. One of the highlights of this deployment--a process which took 18 hours was cut down to 6 minutes. Mark will be discussing the benefits and drawbacks of using F# in Grange's commercial app.

Audio and Video

Deep Fried Bytes Technology Podcast Episode 60: The Futures of the F# Language with Luke Hoban

“In this episode Keith and Woody sit down with F# Program Manager Luke Hoban at TechEd 2010 to discuss the futures of the F# language. Luke gave the guys the scoop on what developers can accomplish with F# and what the team has planned for upcoming releases of F# with Visual Studio.”

General

Dmitri Nesteruk 's Making DSLs in F#

“This article shows that making a DSL in F# is really simple. Of course, the thing about DSLs is they are domain-specific, so for the domain you choose you might encounter a lot more challenges. Have fun!”

Neil Carrier's Basic F# Computation Expressions Using Yield and Combine

“I decided to learn a little bit about computation expressions beyond the basic Bind/Return operations. So I made a goal of learning something about the Yield/Combine operations.”

Neil Carrier's F# Async Computation Expressions: A Tiny Model System

“Continuing my quest to learn computation expressions, I decided to explore from scratch the implementation of basic asynchronous behavior. This post is the result.”

Robert Pickering's What is object oriented programming really all about?

“People often ask me what functional programming is all about and why is it useful. In an attempt to answer this question in a way that is relevant to object oriented programmers it struck me it might be useful to look at what people find useful in modern object oriented programming.”

Celso Axelrud's Vector, Matrix and Linear Algebra in F#

“The following script snippets present the vector and matrix functionalities in Microsoft.Fsharp.Numerics namespace from Fsharp.PowerPack assemble.”

Daniel Markham's Functional TDD: Codd is my Copilot

“You work for the IRS. Your job today is to select a list of people with large bank balances so that you can do some kind of indescribably-complex tax-stuff to them. Your boss would like a list of these guys on his desk by noon.”

Vladimir Matveev's Slides And Samples

“Presentation and code samples from my recent talk on FSUG meeting.”

Stefano Ricciardi's Project Euler Problem 10 in F#

“Calculate the sum of all the primes below two million.”

Ashley Feniello's Project Euler Problem #8

“Largest products of five consecutive digits in this 1000-digit number.”

Ashley Feniello's Project Euler Problem #9

“Pythagorean triplet where a + b + c = 1000”

Ray Dacoco's TabControl in Visual F#

“TabControl is a control that can be used to organize information. It can be utilized as a good alternative to menustrip control.”

Ray Dacoco's Changing the Pointer when the mouse hovers an object

“To change the mouse pointer when the mouse hovers an object, use the Cursor property. All form controls in Visual F# has Cursor property.”

Community

StackOverflow - Does Functional Programming Replace GoF Design Patterns?

“Functional languages have plenty of best practice rules of the form "when you encounter problem X, use code that looks like Y", which is basically what a design pattern is.”

StackOverflow - F# Type declaration possible ala Haskell?

“If you want to keep readable type declarations separately from the implementation, you can use 'fsi' files (F# Signature File).”

A Look Outside

Chris Waggoner's Category Theory

“Category Theory is like Set Theory, but supposedly better. What is it, though?”

F# Discoveries This Week 05/14/2010

RickM — Fri, 14 May 2010 21:06:49 GMT

Today, I’d like to thank all of the F# users on twitter.

Twitter’s a great place to stay up to date on the latest F# happenings and many of the posts you see here are either written by or passed on from members of this community. So, if you are interested in becoming part of the F# Twitter Community, I suggest starting with these frequent F# tweeters: @dmohl, @TigerHasse, @robertpi, @sforkmann, and @ptrelford.

I’ve also been known to occasionally tweet on F# and other programming topics. Now, on to the links.

Brian McNamara’s More F# Screencasts

My previous two screencasts (‘Getting started with F# in VS2010’ and ‘Editing F# source code in VS2010’) have been moved to MSDN, which means they’re now available in a variety of video formats. A new screencast (‘Managing F# projects in VS2010’) has also been added, so check it out!

Robert Pickering’s F# Talks in London

I’ve been in London for the past few days. I arrived Tuesday afternoon and gave at talk at “The F#unctional Londoners Meetup Group” on the Tuesday evening.

James McCaffrey’s Combinations and Permutations with F#

Understanding combinations and permutations is a fundamental skill in software testing. In this month’s Test Run column I show you how to work with combinations and permutations using code written in the new F# language.

Amanda Laucher and Josh Graham’s Pragmatic F# in Action (video)

Amanda Laucher and Josh Graham introduce the audience to F# basics showing some of its main features, emphasizing what makes it better than imperative languages.

Tomas Petricek’s ASP.NET and F# Part 1 – Creating MVC Web Applications in F#

If you want to use F# for creating an MVC application, you have a few options. It should be possible to create the web application solely as an F# project. However, we'll use a more convenient approach. We'll create a standard C# MVC project and move all the actual implementation to an F# library.

Steffen Forkmann’s FAKE – F# Make 1.20.0 Released and
Using a MailboxProcessor to speedup “FAKE – F# MAKE”

Today I released a new bugfix release for “FAKE – F# Make”. We fixed some path and logging issues and as a new feature we introduced the @@ operator which allows to combine paths.

Phillip Trelford’s Trading on IM with F#

The slides from my Trading on IM talk will be attached to this post, and the video/podcast should be appear on the Skills Matter website. I’ll also attach the 100 lines of code for shopping checkout sample, that works with a barcode scanner, I showed at the start of my presentation.

Daniel Mohl’s Integrating F# and Erlang Using OTP.NET

Recently, I ran across a post that talked about a .NET library named OTP.NET. OTP.NET is a port of a Java library named JInterface that allows a .NET application to act as an Erlang node. OTP.NET hasn't been updated in a while and the API is a bit clunky, but the provided functionality is very cool.

Nick Grattan’s Creating Web Parts with F# and
An EDSL for Emitting HTML Tables in Web Parts using F#

When writing web parts in C# for SharePoint the System.Web “table” class or “table” HTML elements are most often used for controlling layout (“div” aficionados keep your ears covered…). The code quickly gets ugly and difficult to manage – there’s no direct control to ensure correct matching of opening and closing of tags. So how about writing an EDSL that provides a syntax and constructs for doing this?

Neil Carrier’s Tiny Expert System using Monads

Below is a tiny expert system implemented using computation expressions. I managed to find a way to use the following computation expression methods: Bind, Delay, and Return.

Neil Carrier’s A Simple DSL: Tokenization to Evaluation,
S-Expressions for Semantic Networks and
A Half-Baked Scheme

This post presents a small example of the above process. It implements a small interpreter which analyzes and evaluates LISP-like prefix expressions involving integers, multiplication, and division. For example: (+ (* 1 2) (* 3 4) evaluates to a data element containing the number 14. To make clear what is happening, be sure and examine the value of tokenList before it is evaluated.

Julien Ortin’s Technical analysis indicators in F# – Bands, Signal and Ehlers

This is part of a series on technical analysis indicators in F#, based on the multi-language TA-Lib. Quick disclaimer : some of these indicators are not verified.

Yin Zhu’s F# for Project Euler Problems

Some problems have two versions of solutions, the version I first learned F# and the version based on my current knowledge of F#. The first version is usually quite easy to understand even if the reader does not know F#, while the second uses some nice F# feature or good functional programming practice in general.

Jon Harrop’s Java vs. F#

What Cliff forgot to mention is that .NET also provides value types and a far more compelling example than complex numbers is the humble hash table.

Tim Ng’s F# + WPF + Events

I recently had to do some travelling for the VS launch event in Las Vegas and QCON event in Beijing. One of the things thats nice about travelling is that it gives you time to do some things you may not otherwise do - in my case, I had a chance to try to (re) learn WPF and see how I can use F# with WPF.

Mark Needham’s Tacit Programming

I realised that this approach quite closely describes what I've been trying to drive towards in my most recent playing around with F# and it's actually quite fun trying to drive any intermediate state or storing of data in variables out of a program and just relying completely on function composition and higher order functions.

Mark Needham’s F#: My current coding approach

I spent a bit of time over the weekend coding a simple generic builder for test objects in F# and I noticed that although there were similarity with the ways I drive code in C# or Java my approach didn't seem to be exactly the same.

Ebru Cucen’s F# vs C# Samples

After my talk at ldnUG yesterday, I got nice suggestions from Zi Makki, and here is the first one: comparison between F# and C#, especially using LINQ. This subject had been quite popular once in a while, now it is probably my time to focus on this subject.

Bjorn Rochel’s Kata StringCalculator in F#

Two meetings ago we decided to do some coding on every meeting. The previous meeting we solved Kata FizzBuzz and on yesterday’s meeting we tried to dance with Roy Osheroves Kata StringCalculator.

Gunnar Peipman’s F# in ASP.NET, mathematics and testing

Starting from Visual Studio 2010 F# is full member of .NET Framework languages family. It is functional language with syntax specific to functional languages but I think it is time for us also notice and study functional languages. In this posting I will show you some examples about cool things other people have done using F#.

Luis Diego Fallas’s Defining mutually recursive classes in F#

As explained in Adventures in F#--Corecursion defining mutually recursive functions requires the use of the and keyword between function definitions. As briefly mentioned in the Type Definitions section of the manual, the and keyword can also be used in types.

Nancy Strickland’s New Features in F# 2.0 Training Video

Describes the new features in F# version 2.0, which comes included in Visual Studio 2010.

DotNetRocks in Boston (with F# Panel)

The panel suggested we add F# to our repertoire and understand its strengths, and use it where it's beneficial. I'm going to take that advice. Bottom line is if I can replace 50 lines of confusing C# code with 10 lines of elegant F#, I've done myself a service.

F# Discoveries This Week 12/29/2009

RickM — Tue, 29 Dec 2009 16:45:42 GMT

It’s been a bit of a light week with the holidays. Although, for the truly dedicated, that’s just a chance to get some quality time in with with a favorite programming language (or to write a poem about it).

Tomas Petricek uses Accelerator in a GPU Game of Life simulation

This article is the second one from a series about using Accelerator from F#. Today, we'll use Accelerator types directly from F# - this is the simplest possible approach and is very similar to the way you'd work with Accelerator in C#.

Robert Sundström explores GCD and LCM in F#

I have spent this evening composing some mathematical functions in F#. So far I have just made two for gcd and lcm and one that can identify prime numbers. I want like to share the code with you.

Robert Pickering describes his work on FunctionalNHibernate

In the future I’ll be looking at how to broadening what you can do with FunctionalNHibernate ClassMap descriptions and improve data access by integrating Linq like features.

Flying Frog solves Rosetta Code’s Data Munging 2 Example

Perhaps the most surprising result is that the F# solutions are extremely concise even when compared with bleeding-edge research languages such as Haskell.

Flying Frog plays with Generic Algorithms

The program begins with a random string of letters and spawns a generation of 200 random mutations of the parent string, selects the fittest mutation (by similarity to an "ideal" string) and uses that individual to spawn the next generation. The ideal string used is "METHINKS IT IS LIKE A WEASEL".

Julien Ortin uses F# to clean up his temporary internet files

A quick and dirty F# script to clean temporary internet files (including Flash cookies which don’t get deleted by the browsers).

Steffen Forkmann observes asynchronous downloads with Rx and F#

This time I will demonstrate how we can use this API and asynchronous workflows to download a couple of websites asynchronous and in parallel.

The PFX Team tours the .NET 4 Parallel Programming Samples

On Code Gallery, we have a plethora of samples that highlight aspects of the .NET Framework 4 that help with writing scalable and efficient parallel applications. This post examines each of those samples, providing an overview of what each provides.

Satnam Singh writes a poem about F#

Distracted by Abstraction - A poem about F#

F# Discoveries This Week 10/11/2009

RickM — Mon, 12 Oct 2009 03:29:00 GMT

This week we find ourselves with a wide range of topics from the fundamental to the advanced. Do enjoy.

Matthew Podwysocki’s Post: Functional Programming Fundamentals Lectures

Earlier this year, I had the privilege to record a Channel 9 video session covering functional programming basics with Erik Meijer and Charles Torre. We covered some of the basics, but at some point you need to go back to the fundamentals in order to truly learn this paradigm. With that, Erik with the help of Charles, have kicked off the Channel 9 lecture series on Functional Programming Fundamentals.

Ade Miller’s Gotchas: Adding Attributes to Properties on Interfaces in F#

I ran into a couple of issues when writing an F# class to be consumed by C#. Specifically when it came to adding attributes to a property declared on an interface.

Steve Horsfield’s F#: Pipelined Monads – Solutions From the Community

The solutions from both Felix and Keith involved creating a single operator that wrapped bind. Felix did this directly and Keith did it by using the computation expression syntax in F#.

Agnius Vasiliauskas’s Evaluating math expressions in F#

We will try to write such universal eval function which accepts arbitrary math expression and returns result to the user. So what are possible ways of implementing such function in F# ?

F# Discoveries This Week 08/09/2009

RickM — Sun, 09 Aug 2009 21:06:00 GMT

This week we have RegEx Processing, Infinite Types, and some mathy code sample blogs I’ve stumbled upon.

Steve Horsfield has completed his F# Regular Expression Processor

This post completes this mini-series on regular expression processing in F#. You can find the complete source code here as well. It has been a good practice for me and I hope you have found the series useful.

StackOverflow: Are Infinite Types (aka Recursive Types) not possible in F#?

I was chatting with Sadek Drobi on twitter when he brought up that F# didn't seem to support Infinite Types. It turns out that in C# you can do something along these lines […] However, after some experimentation on both our parts, we determined that the same in F# seems impossible both implicit and explicitly.

Code Snippets and Examples

While I don’t know who they are run by, I’ve happened upon a couple of blogs which frequently have interesting F# code snippets posted:

The Mad Economist
F# Matrix Inversion (1) - Linear Decomposition
F# Matrix Inversion (2) - The Inverse
F# - Ordinary Least Squares (OLS)
F# - OLS (R-Square) - Array2D.init

F# Code
Lambda Calculus Normal Order Reducer
GroupBy Rx Combinator
Reactive Linq in F#

Discoveries This Week 02/06/2009

RickM — Fri, 06 Feb 2009 16:24:00 GMT

Some interesting gems this week. Revit, Closures and MathTools won the day. However, I do hope you'll take a look at the IL post as well.

Blog – Jeremy Tammik’s Use F# Directly in Revit

In Jeremy’s post he discusses what is initially necessary to get F# and Revit working together. He also provides a sample of a Revit addin written in F#.

Revit is Autodesk’s architecture and design studio. It allows physical engineers to coordinate and play with, design and visualize data while integrating directly with AutoCad. It also provides a .NET 2.0 API. Given F#’s support for units as well as it’s concise and mathy style, it makes sense that it would be an ideal language for engineers.

Site - WikiBooks FSharp Programming

Before I stumbled upon this site, I had never head of of WikiBooks. That’s why I was incredibly surprised to find that it has the best online general F# reference around. It has extensive sections on functional, immutable and imperative programming with rich examples and references to the math behind the ideas presented. It’s a great site to have at hand for both those learning about the language and those experienced but still needing to occasionally look something small up.

StackOverflow - A practical example of a closure in F#

Learning how to program functionally is much more than just learning some new ideas and a new syntax. It comes along with a ton of new jargon, some of which can be quite foreign sounding. I find that it often turns out that the jargon actually represents a very simple idea and that becomes immediately obvious when discussed with a simple example.

Software – FSharp.MathTools

As you might have suspected by its name, MathTools is an extensive set of mathematics libraries for F#. It provides, among other things, statistical functions, fast fourier transforms, optimization algorithms, Matlab compatibility and extended mathematical notation. With a little development this combined with VSLab could provide a viable alternative to tools like Matlab while still allowing for collaboration with colleagues.

Article – Introduction to IL Assembly Language

It’s the responsibility of any serious programmer to know how how his or her tools work all the way down the chain. In this relatively short article (given the topic) everything you would need to write a .NET compiler is distilled. It’s the best reference of it’s kind I’ve seen.