new keyword

[Robert Kuzelj]

Hi,

is there any specific reason why 'ordinary' classes must be instantiated via the 'new' keyword and now by simply calling the constructor function like with DUs?

It would make operating with external classes much more pleasant (from a F# POV).

so instead of

let v = new SomeView(Color = green)

let v' = SomeView(Color = green)

Best regards

Robert

[Isaac Abraham]

You don’t need to use the new keyword at all. Indeed in F#4 constructors are treated as first-class functions so you can use them within e.g. List.map etc..

 

The only time you’ll get a warning for not using the new keyword is for classes that implement IDisposable.

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[Robert Kuzelj]

Hey Issac,

thanks for that - I must admit I read that but forgotten about meanwhile.

Reason for that is that I am using Xamarin and will be stuck with f# 3.1 for some while. :-(

best regards

Robert

[Loïc Denuzière]

You can actually call this:

    let v = SomeView(Color = green)

in F# 3.x too, it will work just fine.

What you do need F# 4 for is if you wanted to pass `SomeView` as a function, for example if you wanted to do something like this:

    let v = List.map SomeView [green; red; blue]

[Robert Kuzelj]

Hi Loic,

    let v = SomeView(Color = green)

in F# 3.x too, it will work just fine.

Doesnt work for me in Xamarin ...