The semantics for this is the same as in F# (probably because F# is based on OCaml): function allows the use of pattern matching (i.e. |), but consequently it can be passed only one argument. function p_1 -> exp_1 | … | p_n -> exp_n is equivalent to fun exp -> match exp with p_1 … Read more
It’s the function composition operator. More info on Chris Smith’s blogpost. Introducing the Function Composition operator (>>): let inline (>>) f g x = g(f x) Which reads as: given two functions, f and g, and a value, x, compute the result of f of x and pass that result to g. The interesting thing … Read more
If you want to use the built-in F# formatting engine (and avoid implementing the same thing yourself), you can use F# printing functions such as printfn. You can give it a format specifier to print an entire list (using F# formatting) or print just a first few elements (which happens when you call ToString): > … Read more
F# is my language of choice, but I’d strongly recommend learning them all. They are all quite different and interesting in their own right. Here’s a quick over view to each one (with perhaps a slight F# bias), you can easily find more info by googling: F# – is a language that makes it easy … Read more
The usual idiom is to define the function to take one argument of type Unit (let functionName () = 42). It will then be called as functionName (). (The unit type has only one value, which is ().)
Use a tuple as your sort key: myList |> Seq.sortBy (fun x -> x.Something, x.SomethingElse)
In order to switch ASP.NET Core 3.0 back to use JSON.NET, you will need to reference the Microsoft.AspNetCore.Mvc.NewtonsoftJson NuGet package. That will contain the AddNewtonsoftJson extension method. In C#, this would look like this: services.AddControllers() .AddNewtonsoftJson(); So assuming that I understand enough of F#, I would say that your call would be correct if you … Read more
As the compiler points out, there is no type that can be assigned to x so that the expression (x x) is well-typed (this isn’t strictly true; you can explicitly type x as obj->_ – see my last paragraph). You can work around this issue by declaring a recursive type so that a very similar … Read more
Try List.ofSeq in the Microsoft.FSharp.Collections namespace. # List.ofSeq : seq<‘T> -> ‘T list It’s not specifically for System.Collections.Generic.List<T>, but for IEnumerable<T> (seq<‘T> in F#) types in general, so it should still work. (It’s also not strictly built into the F# language, but neither is List<T> built into C# or VB.NET. Those are all part of … Read more
Go here and download fsharp.zip Unzip it and open the created folder Open the terminal and run ./install-mono.sh as root (On some systems, it is necessary to convert the newline characters in that script from CRLF to LF) This will give you the basic functionality which means you will be able to run “mono fsi.exe” … Read more