Question

I have the following types:

type ColorCounter = 
    {

        Count : int
        Color : Microsoft.Xna.Framework.Color 

    }

let AvailableColors : Map<uint32,ColorCounter> = .....

I would like to iterate through the Map and return a List . I wrote the following function that doesn’t compile:

let AvailableColorList(map : Map<uint32,ColorCounter>) : List<Microsoft.Xna.Framework.Color> = 
     let colorSeq = seq {

        map |> Map.iter (fun key col -> yield col.Color)  
     }
     colorSeq |> Seq.toList

I guess I’m doing something wrong with the syntax of the function passed to iter, but I’ve not find any suitable example that shows me how to do that.

Could anyone help me?What’s my error? How can I fix the code above?

Answer 1

I think you want this

let AvailableColorList(map : Map<uint32,ColorCounter>) = 
    ResizeArray(map |> Seq.map (fun (KeyValue(_, col)) -> col.Color))

You’re mixing a sequence comprehension and map, which are two different ways of doing the same thing.

You could also write it this way

let AvailableColorList(map : Map<uint32,ColorCounter>) = 
    ResizeArray([ for KeyValue(_, col) in map -> col.Color ])