F# |> I <3 | Pirrmann's train of thought

The post says F# has shaped the author’s everyday C# coding for years, and that a recent work project let him use F# for real. He also says the open-sourcing of Roslyn was welcome, but the bigger news for him was that Visual F# now accepts contributions, which makes him expect more from the language.

Reading notes

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• The author says he has been writing about F# for a while and has now gone “totally” over to F#.
• He presents a kata about values with uncertainty and operations that manipulate them.
• He models a value and its precision with a Number type holding two floats.
• He defines a +- operator to build values like 4.0 +- 1.0.
• He uses FsUnit tests to check that a number equals itself and that addition combines values and accuracies.
• He writes a generic combine function that evaluates an operator on the boundary values, then rebuilds the result from the minimum and maximum.
• He adds operator overloading so +, -, /, and Pow all use the same combine logic.
• He thanks @luketopia for the Twitter exchange and for the trick that lets ** be passed as an argument with spaces around the operator.