Statically resolved member constraints

Constraints

type SyntaxToken = string

type X =
    {
        SomeProperty: string
    } with
    member this.AddModifiers(tokens:SyntaxToken array) =
        { this with
            SomeProperty = sprintf "%s + %s" (this.SomeProperty) (System.String.Join(",", tokens)) }

type Y =
    | SomeDUType of int
    | SomeOtherDUType of int with
    member this.AddModifiers(tokens:SyntaxToken array) =
        match this with
        | SomeDUType i -> SomeOtherDUType (i+1)
        | SomeOtherDUType i -> SomeDUType (i+1)

let inline addModifiers< ^T when ^T : (member AddModifiers : SyntaxToken array -> ^T)> tokens (input:^T) =
    (^T : (member AddModifiers : SyntaxToken array -> ^T) (input, tokens))

// tests
let x = { SomeProperty = "Test" } |> addModifiers [|"a";"b"|]
let y = SomeDUType 1 |> addModifiers [|"a";"b"|]

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