Mutable Dictionary DSL

struct-builder.fs

open System.Collections.Generic

[<Struct>]
type DictBuilder<'a, 'b when 'a: equality> =
  val d: Dictionary<'a,'b>
  new(()) = { d = Dictionary<'a, 'b>() }
  member this.Yield (key, value) = 
    this.d.Add(key, value)
  member this.Zero() = this.d
  member _.Combine(_, _) = ()
  member _.Delay f = f()
  member this.Run _ = this.d

let mutDict<'a,'b when 'a: equality> = DictBuilder<'a, 'b>(())

let a =
    mutDict {
        1,3
        2,4
        3,5
    }
    
val a : Dictionary<int,int> = dict [(1, 3); (2, 4); (3, 5)]