Sergey Tihon's Blog

F# Weekly #35, 2014

01/09/2014F# Weekly2 Comments

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

Do not waste your time and jump in F# OSS development starting from Up For Grabs issues.
Visual F# PowerTools v1.4.5 are published with fixes for annoying bugs on F# project system and unused opens.
FAKE 3.4 is released with a HipChat notification helper, fixes to FAKE.Deploy, and some Xamarin.iOS and Xamarin.Android helpers.
F# semantic syntax highlighting is available in Xamarin Studio!
Reed Copsey, Jr. is posted an update on the F# logo project.
Taha Hachana is shared “Creating Google Maps charts with FsPlot“.
Check out the F# sessions at October’s SVCC.
“Circular Calculations” is a new F# Coding Dojo from Liam McLennan.
iFSharp Notebook v2.0.1 is released.
FSharp.Data v2.0.14 is out.

Core and Lang News

Please take a look at FAKE script for Visual F#, try it and comment.
Recently accepted PRs:
- “fix error message in set” by Jack Pappas.
- “F# Interactive freezes when printing values with very long lines” by Vladimir Matveev.
- “instruction identifiers should be marked as literals to help the compiler optimize code using them” by Jack Pappas.
- “change verifyseqsequal error message” by Patrick McDonald.
- “optimizer literals” by Jack Pappas.
Recently proposed PRs (Please review and comment):
- “perf. optimization – seq.toarray” by ReedCopsey.
- “change verifyseqsequal error message” by Patrick MacDonald.
- “implement seq.permute” by Patrick MacDonald.
- “fix message of warning fs2003” by esada.
- “help first time users of fsi” by esada
Mårten Rånge works on performance optimizations for F# expression.

Videos/Presentations/Courses

“FParsec Hands On – F#unctional Londoners 2014” by Phillip Trelford.
“Write Clean Code using the Pipelining Operator in F#” with Jorge Fioranelli.
“F# News – Aug-2014” with Troy Kershaw.

Blogs

Amir Barylko blogged “Acceptance Testing Made Easy with F# and Canopy Why acceptance testing?“.
Mårten Rånge wrote about “Abstractions vs Performance, a compiler perspective“.
Ryan Riley posted “Bundling and Minification with Web Essentials“.
Larry O’Brien blogged “Xamarin.Forms Programming in F#“.
Steve Link wrote about “Developing an ISeries Intranet Based LOB Application“.
Karlkim Suwanmongkol posted “Trying numl on OSX with F# and Xamarin“.
David Falkner blogged “Reason #714 that I’m loving F#: Discriminated Unions“.
Andrea Magnorsky wrote “F#n and games“.
Phil Trelford posted “FParsec Tutorial“.
Alex Hardwicke blogged “Pattern Matching“.
masuda wrote “最新の FsYacc/lex 環境で chulang を作成するときのメモ“.
htid46 shared “F# のデバッグ方法 #fsharp“.
masuda posted “TypeProviderで生成したクラスをC#で使うための方法“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #34

F# Weekly #34, 2014

25/08/2014F# Weekly1 Comment

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

Round 3 of voting for the new F# logo is underway! Please vote for your favorite!
Functional Geekery Episode 14 is out with Richard Minerich.
FsPlot v0.6 is released with an FSharp.Charting like API and PNG screenshot export.
Welcome to join “F# Web Stack” forum.
Cross-Platform Development Platform Xamarin Raises $54M Series C.
F# cheatsheet was updated.
CloudSharper v0.9.17 is out.
FSharp.Data v2.0.10 is out.

Core and Lang News

Announced the release of Visual F# Tools 3.1.2!
ReedCopsey sent PRs:
- updated project templates.
- perf. optimization – seq.toarray.
OkayX6 sent PR with “groupby implementation“.
Mårten Rånge sent PR that “allow use on member binding“.

Videos/Presentations/Courses

“A Day in the Life of a Functional Data Scientist” with Richard Minerich.
Taking F# to the Masses with CloudSharper (and Adam Granicz!).
F# Web Development with Ryan Riley. (+samples).
Reaching personal goals with F#, literally! with Nelson Lin
F# + SignalR + Xamarin.Forms with Juan M Gómez.

Blogs

ML Dialects and Friends: OCaml, F#, Scala, Haskell.
Kevin Cantù posted “Operator precedence: F# and Haskell“.
Richard Dalton finished his “Active Patterns” series with “Active Patterns : Choices and Nesting“.
Eirik Tsarpalis wrote technical overview of FsPickler.
Aleksander Heintz blogged “Language Support in the language you’re supporting (or eating your own dogfood)“.
Anh-Dung Phan posted “F# and linear programming: an introduction to Z3 optimization API“.
Jamie Dixon wrote “Consuming and Analyzing Census Data Using F#“.
Simon Fowler announced “WebSharper UI.Next Version 0.1.31.32“.
Vince Avery wrote about “Timings and GC in C#“.
Daniel Bradley posted “Reflections of a .Net’er in a Node World (Some F# Language Ideas)“.
Senthil Kumar published “FSIAnyCPU Feature in Visual Studio 2013“.
Tim Jones blogged “Writing a MiniC-to-MSIL compiler in F# – Part 4 – Building the intermediate representation“.
Ronnie Holm posted “Querying SharePoint 2007 lists with WSDL, XML, and Regex F# type providers“.
Ramón Soto Mathiesen wrote “F# – A better way to use OData with JavaScript and SDK.REST.js on CRM2011 and CRM2013“.
Mathias Brandewinder blogged “Coding in the Age of Mobility: @fsibot 0.1 is out!“.
7shi wrote “Haskellの型クラスとF#のインターフェース“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #33

F# Weekly #33, 2014

18/08/201418/08/2014F# Weekly1 Comment

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

Visual F# PowerTools v1.4.0 is out with graying out unused opens, full support for VS 14 and much more besides.
Vote for “Support for collectible assemblies” if you want to see more improvements for F# Type Providers and REPL.
FSharp.Compiler.Service v0.0.59 is out.
FSharp.Formatting & FSharp.Formatting.CommandTool v2.4.21 are out.
FSharp.Data.SqlClient v1.3.2 is out.
F# Azure Storage Type Provider v1.1.0 is out.
CloudSharper v0.9.16 is out, allowing you to develop custom editors.
Akka.FSharp v0.6.3 is out.
Adam Granicz shared “PhoneJS for WebSharper sample“.
Interested in the best options for serialization in F#? Checkout the FsPickler performance page.
Sindunata Sudarmaji created chocolatey package for Visual F# Tools.
Taha Hachana shower “jQuery Image Carousel“.

Core and Lang News

Help Visual F# Team out by trying the release candidate for Visual F# Tools 3.1.2.
Patrick Mcdonald implemented a F# 4.0 feature (implement skipwhile) – review his PR.
‘Cannot add reference to F# PCL project‘ F#issue is fixed.

Videos/Presentations/Courses

PluralSight course “F# Functional Data Structures” with Kit Eason.
A new Course “F# via Machine Learning” with Mathias Brandewinder was announced.
“FSharp.Data Poster” by Tomas Petricek.

Blogs

Juan M Gómez blogged “Hello CocosSharp from FSharp!“.
Phil Trelford posted “Running TAP“.
Ryan Riley shared:
- “WebSharper UI Improvements“.
- “F# Web Stack Group“.
Richard Dalton presented:
Ronnie Holm posted “Querying Azure Active Directory through Azure Graph API with F#“.
Andrew Cherry wrote:
- “aether — total & partial lenses for f#“.
- “aether — brief guide“.
Marius Schulz posted “Learn the Basics of F# with Project Euler“.
Ashley Towns blogged “Running .Net on heroku“.
Jamie Dixon wrote “Controlling Servos Using Netdunio and Phidgets“.
masuda posted:
- “PCL対応のTypeProviderを作…れるのかな？の巻“.
- “Xamarin.iOS/Android に対応している Profile78 とは何か？“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #32

F# Weekly #32, 2014

11/08/2014F# Weekly1 Comment

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

Enjoy F# trending projects on GitHub!
CloudSharper 0.9.15.2 is released.
Alea.cuBase 1.3 is released.
AkkaDotNet v0.6.2 is released with improved F# support.
Mono 3.6 is out, so no need to build mono from scratch anymore.
Streams (top trending F# project) v0.1.5 is on NuGet: introducing ParStream and new ResizeArray functions.
Join FSharp.Formatting developing starting from up-for-grabs items.
Taha Hachana created Google geo charts with FsPlot.
Eirik Tsarpalis has updated FsPickler performance page.
Dave Thomas republished a bunch of posts from his old blog.
Anton Tayanovskyy joined Tachyus F# team.
Jérémie Chassaing presented FsUno.Prod.
Yan Cui updated JSON serializers benchmark.

Core and Lang News

A new F# compiler bug was found “Wrong code generated for “Subscribe” method calls“.
Patrick MacDonald implemented new features (please review):
- add mapi2 to seq
- add iteri2 to seq

Videos/Presentations

“F#で動かすraspberry pi+lego mindstorms” by moonmile.
“どこでも使えるF sharp again pub” by Masahiko Miyasaka.
“F# intro” by yoko ishikuro.

Blogs

Cameron Taggart blogged “Read & Write RPM Files from F#“.
Johan von Tangen Sivertsen posted “C# F# Excel parsing“.
Jamie Dixon wrote “Neural Network Part 3: Perceptrons“.
Aleksander Heintz blogged “vNext with a touch of functional“.
Ronnie Holm posted “Querying Active Directory organizational units, groups, and members with F#“.
Bartosz Sypytkowski blogged “Actor Supervisors in Akka.NET FSharp API“.
Richard Dalton presented:
Pepijn de Vos wrote about “Learning F# as a lesson in feminism“.
Nicholas Wolverson blogged “Strong typing for SignalR“.
Richard Dalton published “ByRef Params: You gotta love F#“.
Juan M Gómez posted “Creando un TypeProvider“.
Alex Casquete wrote about “Workflows asíncronos con F#“.
masuda published “Xamarin.Forms の TypeProvider を作ろうとしたが断念したの巻“.
htid46 wrote “F# のデバッグ方法 #fsharp“.
h_sakurai posted “FSharpで学ぶ四則演算コンパイラ“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #31

F# Weekly #31, 2014

04/08/2014F# Weekly1 Comment

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

Enjoy F# chat on StackOverflow.
WebSharper UI.Next now has a shiny new website.
First wave of samples for WebSharper bindings to WinJS 2.0.1.
Taha Hachana shared his first WebSharper UI.Next experiments.
FSCL 1.3 is online(New project structure, NuGet packages, FSCL organisation, GitHub pages with docs and tutorials)!
The HomeBrew build for F# is unwell, a problem with resgen.exe. Can any homebrew + mono experts help? 🙂
F# FreeBSD package is updated to 3.1.1.25. All you need is to ‘pkg install fsharp’ (well, run ‘pkg update’ first).
A new interesting SO reply by Edinburgh University’s James Cheney about a new approach to dynamic LINQ queries in F#.

Core and Lang News

Please install the latest version of Visual F# Tools preview. Help to find the remaining issues!
Check out Don’s prototype for “Allow static arguments to Type Provider methods eg M<“ABC”>()“. (+docs)
Is anyone interested in working on speeding up the F# compiler?
Mårten Rånge was tweaked the F# compiler to generate faster IL code for ‘for x in xs do …’ when xs is a ‘T list.
A new issue in Visual F# 3.1.2 “Visual F# 3.1.2 build actions missing“.

Videos/Presentations

“Functional thinking, a universal tool for the digital world” with Nicolas Rolland.
“Intoduction to Homotopy Type Therory” by Jack Fox.
“Option Types using F#” by Jorge Fioranelli.
“F#事例発表” by bleis tift.

Blogs

Mathias Brandewinder blogged “Picasquez vs Velasso: Classics Mashup with F#“.
Palladium Consulting posted “How Many Children are Leaving Central America: F# Edition“.
Mark Seemann blogged “How to create a pure F# ASP.NET Web API project“.
Simon Fowler posted “Animating single-page applications with UI.Next“.
Richard Dalton wrote “Active Patterns: Single Case Total Pattern“.
Senthil Kumar posted “How to Find the Sum of odd numbers from 0 to 100 in F#?“.
htid46 wrote “Visual F# Power Tools の紹介“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #30

F# Weekly #30, 2014

28/07/2014F# Weekly1 Comment

Welcome to F# Weekly,

A roundup of F# content from this past week:

News

If you want to suggest a new feature for the F# addin in Xamarin Studio, remember to add it to user voice.
Visual F# Power Tools can show you unused open declarations.
New F# meetup in Toronto.
Call to F# speakers. Help to put on an F# track at the world’s largest SiliconValley CodeCamp in October.
A template for F#-branded logos is now part of ProjectScaffold! Download and create a logo for your project.
WebSharper site was re-styled.
Dmitry Morozov works on FSharp.Desktop.UI (F# MVC for WPF) and new samples.
Isaac Abraham is almost ready to introduce queue support to the F# Azure storage type provider.
ParStream.sortBy is up to 3x faster than PSeq.sortBy.

Core and Lang News

Visual F# Tools will be moving to GitHub!
Try out the latest preview release of F# 3.1.2 and help Visual F# team to ensure that it is ready for release!
The most elegant PR to F# Compiler.
Feedback wanted: if you downloaded the F# preview, did you use F# from within VS or from the shell?
Want to work on F#? Well here is an issue to whet your appetite “Object Initializer Intellisense Broken“.
Interested in improving F# and easing F#-C# interop? This issue is for you “Improve optional parameter interop between F# and C#“.
Steffen Forkmann proposed a FAKE build script for Visual F#.

Videos/Presentations

“Tackle UI with Reactive DOM in F# and WebSharper” by Anton Tayanovskyy.
“Doing Data Science with F#” by Tomas Petricek.
“モナドハンズオン前座 ” by bleis tift.

Blogs

Simon Fowler wrote “WebSharper.UI.Next: An Introduction“.
Jamie Dixon blogged “Neural Network Part 2: Perceptrons“.
Sergey Tihon wrote “F# Kung Fu #4: Avoid using relative paths in #r directives“.
Rahul Garg published “F# microbenchmark study“.
Miguel de Icaza published “Mono’s performance team“.
Phil Trelford blogged “My First Xamarin Mobile App“.
Ronnie Holm posted “Trustpilot challenge: dictionary-based multi-word anagram solver with a twist“.
Anton Tayanovskyy wrote “WebSharper.UI.Next: Declarative Animation“.
Sergio De Simone posted “F# Native App Development on iOS and Android“.
Tim Sneed blogged “Building an F# app using Xamarin“.
Bernard Hsu posted “Calling Fortran assemblies from .NET“.
Simon Fowler wrote about “Structuring Web Applications with WebSharper.UI.Next“.
Anton Tayanovskyy posted “The fatal attraction of FRP“.
Tim Sneed wrote about “Add a refresh navigation button to your xamarin F# app“.
Cameron Taggart published “Complete Graph on Android“.
Matt Button shared “A Basic Stock Trading Backtesting System For F# Using Ta-Lib And FSharp.Data“.
Anton Tayanovskyy announced “UI.Next available“.
Bernard Hsu blogged “Genetics, Evolution of Color, and the French Revolution in F# Xamarin iOS“.
Michał Łusiak posted “Talking F# in Warsaw“.
David Tchepak wrote about “F# assertion libraries“.
Richard Dalton blogged “Learning To Think Functionally: Types, Maps and Sets“.
Yan Cui posted “Here Be Monsters – Message broker that links all things“.
Павел Осадчук написал “Разработка приложения на Android с помощью Xamarin и F#“.
Olivier Dahan published “Programmer en pensant fonctionnel (F#)–Partie 6“.
masuda wrote about “Xamarin.Forms の XAML を F# から使うために XamlTypeProvider を使う“.
masuda posted “Xamarin.Forms+F# で Navigation.PushAsync を使うときの注意“.

That’s all for now. Have a great week.

Previous F# Weekly edition – #29

F# Kung Fu #4: Avoid using relative paths in #r directives

23/07/201424/07/2014F#, Tips and Tricks6 Comments

Today, Vladimir Makarov faced with quite interesting ‘bug'(very unexpected behavior) of FSI. The initial goal was quite simple – count number of NuGet packages, which have “ASP.NET” in title. As a result, there was created a script that perfectly works in compiled form and crashes in FSI, here it is:

#r "../packages/nuget.core.2.8.2/lib/net40-Client/Nuget.Core.dll"
#r "System.Xml.Linq.dll"

let repository =
    NuGet.PackageRepositoryFactory.Default.CreateRepository
        "https://nuget.org/api/v2"

let aspnet = query {
    for p in repository.GetPackages() do
    where (p.Title.Contains "ASP.NET")
    count
}

When we run this in FSI we got an exception

System.ArgumentException: Incorrect instance type
Parameter name: obj
at Microsoft.FSharp.Quotations.PatternsModule.mkInstanceMethodCall(FSharpExpr obj, MethodInfo minfo, FSharpList`1 args)
at Microsoft.FSharp.Quotations.ExprShapeModule.RebuildShapeCombination(Object shape, FSharpList`1 arguments)
at Microsoft.FSharp.Primitives.Basics.List.map[T,TResult](FSharpFunc`2 mapping, FSharpList`1 x)
at Microsoft.FSharp.Linq.QueryModule.walk@933-1[a](FSharpFunc`2 f, FSharpExpr p)
at Microsoft.FSharp.Linq.QueryModule.EvalNonNestedInner(CanEliminate canElim, FSharpExpr queryProducingSequence)
at Microsoft.FSharp.Linq.QueryModule.EvalNonNestedOuter(CanEliminate canElim, FSharpExpr tm)
at Microsoft.FSharp.Linq.QueryModule.clo@1741-1.Microsoft-FSharp-Linq-ForwardDeclarations-IQueryMethods-Execute[a,b](FSharpExpr`1 )
at <StartupCode$FSI_0002>.$FSI_0002.main@() in D:\Downloads\test.fsx:line 4

When we looked more carefully to FSI output, we saw that:

WAT? FSI lies to us?! First message says that correct version of DLL was referenced, but then FSI loads completely wrong old version installed with ASP.NET. Why? Let’s check what #r actually does…

#r means to reference by dll-path; focusing on name. This means that FSI will use the file name first, looking in the system-wide search path and only then try to use the string after #r as a directory-relative hint

So that means, #r is not reliable way to reference assemblies. You can get into the situation when your script depends on the environment: assemblies in GAC, installed software (like version of ASP.NET) and so on. To avoid this it is better to explicitly specify an assembly search path (#I) and then reference the assembly:

#I "../packages/nuget.core.2.8.2/lib/net40-Client"
#r "Nuget.Core.dll"
#r "System.Xml.Linq.dll"

let repository =
    NuGet.PackageRepositoryFactory.Default.CreateRepository
        "https://nuget.org/api/v2"

let aspnet = query {
    for p in repository.GetPackages() do
    where (p.Title.Contains "ASP.NET")
    count
}

Thanks to Vladimir Makarov for interesting challenge and be careful in your scripts.