How to loop through discriminated union cases and call thier member functions on them?

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The goal is the loop through each descrimintated union cases and print out the description for each case e.g

type car = 
| Benz 
| Honda 
    member this.description() = 
        match this with 
        |Benz -> "Benz description"
        |Honda -> "Honda description"

The calling code would use FSharpType.GetUnionCases typeof<Car> and loop through the union cases.

Is this possible to achieve in F#?

f#
1 Answers

I think you can use FSharpValue.MakeUnion. This example will return a sequence of tuples with the union type and description:

type Car = 
| Benz 
| Honda 
    member this.description() = 
        match this with 
        |Benz -> "Benz description"
        |Honda -> "Honda description"

FSharpType.GetUnionCases typeof<Car>
|> Seq.map (fun uci ->
    let c = FSharpValue.MakeUnion(uci, [||]) :?> Car
    (c, c.description()))

Example:

val it: seq<car * string> =
  seq [(Benz, "Benz description"); (Honda, "Honda description")]
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