{"id":1140,"date":"2012-01-29T10:34:35","date_gmt":"2012-01-29T10:34:35","guid":{"rendered":"http:\/\/www.navision-blog.de\/?p=1140"},"modified":"2012-01-29T17:32:32","modified_gmt":"2012-01-29T17:32:32","slug":"why-do-we-need-partial-application-part-1-of-n-fluent-interfaces-and-piping","status":"publish","type":"post","link":"http:\/\/www.navision-blog.de\/blog\/2012\/01\/29\/why-do-we-need-partial-application-part-1-of-n-fluent-interfaces-and-piping\/","title":{"rendered":"Why do we need partial application? – Part 1 of n – Fluent interfaces and piping"},"content":{"rendered":"

My last blog post<\/a> was yet another introduction to Currying<\/a> and Partial application<\/a>. Now I want to put the focus more on the why<\/strong><\/font> part. Why do we want to have our functions in curryied form most of the time? This is the first part of a small blog post series and shows partial application in F# pipelines.<\/p>\n

Using \u201cFluent interfaces<\/a>\u201d is a popular technique to write code in a more readable form. In languages like C# they also provide a way to create the code much faster. On every . we get IntelliSense and this gives us a \u201cfluid\u201d way of writing.<\/p>\n

Let\u2019s consider the following task: we want to compute the sum of the square roots of all odd numbers between 1 and 100. In C# we can use the LINQ method chaining approach in order to do something like this:<\/p>\n

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Now how does this look in F#? It\u2019s basically the same. We replace every . with the |> operator and use the analogous Seq.* functions:<\/p>\n

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Oups! What happened here? The F# compiler noticed a type error. Math.Sqrt<\/strong> needs a float as input but we gave it an int. C# uses implicit casts between int and float so we didn\u2019t noticed the problem there. Implicit casts are a little bit problematic, at least if you want to have proper type inference<\/a> so F# doesn\u2019t have this feature. No problem, we are programmers so let\u2019s add the conversion manually:<\/p>\n