F# : wrap tuples into multiple lines

Question

Let's say I have a simple Tree :

type Tree =
    | BinaryNode of Tree * int * Tree
    | Tip 

    member this.Sum =
        match this with
        | Tip -> 0
        | BinaryNode(left, value, right) -> left.Sum + value + right.Sum

and I define a tree by :

let tree = BinaryNode( BinaryNode( Tip, 2, Tip ), 1, BinaryNode( Tip, 3, Tip ))

But I think it's really hard to read if we have a tree with multiple nodes. So I wrap it into multiple lines as below :

[<EntryPoint>]
let main argv =

    let tree = 
        BinaryNode( 
            BinaryNode( Tip, 2, Tip ), 
            1, 
            BinaryNode( Tip, 3, Tip )
        )

    printf "%A" (tree.Sum)

    0

The above code works as expected in Visual Studio. But when I use Visual Studio Code with Ionide , it reminds me that :

Lint: Comma in tuple instantiation should be followed by single space.

My question :

1. I'm confused. Is it bad to wrap tuples into multiple lines ?
2. If not, how to make the lint shut up ?
3. If the answer is Yes, how to improve the readability when we have ten nodes ?

Answer 1

It don't think it's necessarily bad to do. Well, I hope not, since I do it all the time. Especially in cases like this, where the line would otherwise be much too wide, to be pleasent to read.

As far as I can tell, Ionide uses FSharpLint. According to the docs, individual warnings can be disabled on a project level, by placing an XML file called Settings.FSharpLint in the project folder, with the desired configuration.

I think, in your case, the file should have the following content:

<?xml version="1.0" encoding="utf-8"?>
<FSharpLintSettings>
  <Analysers>
    <TupleCommaSpacing>
      <Enabled>false</Enabled>
    </TupleCommaSpacing>
  </Analysers>
</FSharpLintSettings>