Many advances in programming language design are driven by some practical motivations. Sometimes, the practical motivations are easy to see - for example, when they come from some external change such as the rise of multi-core processors. Sometimes, discovering the practical motivations is a tricky task - perhaps because everyone is used to a certain way of doing things that we do not even see how poor our current solution is. The following two examples are related to the work done in F# (because this i[...]

× 実際の結果を見るにはここをクリック！ ここ数年、日本のF# コミュニティは「F# Advent Calendar」というイベントを開催しています (2010年、 2011年、 2012年、 そして 今年)。 これはadvent dayごとに1人ずつ、F#に関連した何かしら興味深い記事を作成するというものです。 私は去年からTwitterでadvent calendarをチェックしていて、 今年からは私も参加しようと思い、記事を書きたいと申し出ました。 そうしたところ、数名の方からの協力を得ることができました。 @igeta には参加手続きの諸々とレビューを、 @yukitos にはこの記事の翻訳を、そして @gab_km には翻訳のレビューをしていただきました。 ありがとう！ けれども何についての記事を書くのがよいのでしょう？ 過去一年にわたって、F#コミュニティで開発されているF#のオープンソースライブラリやプロジェクトを いくつか紹介できるような記事がよさそうです。 それと同時に、日本に関連のあるトピックが何かないものでしょうか？ 少し考えてみたところ、以下のようなプラ[...]

F# computation expressions are the syntactic language mechanism that is used by features like sequence expressions and asynchronous workflows. The aim of F# computation expressions is to provide a single syntactic mechanism that provides convenient notation for writing a wide range of computations. The syntactic mechanisms that are unified by computation expressions include Haskell do notation and list comprehensions, C# iterators, asynchronous methods and LINQ queries, Scala for comprehensions and Pyth[...]

The hard part about successful open-source development is not putting the first version of your source code on GitHub. The hard part is what comes next. First of all, there are community aspects - making sure that the project fits well with other work in the area, engaging the community and contributors, planing future directions for the project and so on. Secondly, there is an infrastructural side - making sure that there is a package (on NuGet in the F# world), easy to run and useful tests and also[...]

In a recent StackOverflow question the poster asked about the difference between tupled and curried form of a function in F#. In F#, you can use pattern matching to easily define a function that takes a tuple as an argument. For example, the poster's function was a simple calculation that multiplies the number of units sold n by the price p: 1: let salesTuple (price, count) = price * (float count) The function takes a single argument of type Tuple<float, int> (or, using the nicer F# notation float * int[...]