Proof of concep of using Parser from https://gist.github.com/mastoj/44463deadf28c3efdb0ca3a91b3ccb9c

Main.fsx

#r "../node_modules/fable-core/Fable.Core.dll"
#load "libs/Parser.fsx"
#load "Helpers.fsx"


namespace Herebris.BridgeStream

open Fable
open Fable.Import
open Fable.Import.Browser

open Fable.Helpers.Virtualdom
open Fable.Helpers.Virtualdom.Html

open System
open Parser.RouteParser
open Parser.Parsing

module Main =


  type Route =
    | Home of string
    | Add of int * int
    | Sub of int * int

  type Model =
    { CurrentRoute: Route option
      ValueA: int
      ValueB: int }

  type Action =
    | Sum of int * int
    | Sub of int * int
    | NewRoute of Route option
    | PushRoute of Route

  let update model action =
    match action with
    | NewRoute route ->
      console.log "new route"
      { model with CurrentRoute = route }, []
    | _ -> model, []

  let view model =
    div
      []
      [
        text "coucou"
        button
          [ onMouseClick (fun _ -> PushRoute (Add (3,5))) ]
          [ text "Add 3 + 5" ]
      ]

  let routes : (string -> Result<Route>) list =
    [ runM Home (pstring "" |> _end)
      runM Add (pstring "add" </.> pint </> pint |> _end)
      // Add the full reference to Sub otherwise the compiler
      // complain about Route and Action types
      runM Route.Sub (pstring "sub" </.> pint </> pint |> _end) ]

  let navigationOnChangeProducer h =
    window.addEventListener_hashchange(fun _ ->
      let newRoute =
        window.location.hash.Substring 1 // Remove the first char because we use hash url in this sample
        |> choose routes
      h (NewRoute newRoute)
      null
    )

  let navigationSubscriber appEvent =
    match appEvent with
    | ActionReceived msg ->
      match msg with
      | PushRoute route ->
        match route with
        | Add (a,b) ->
          let newUrl = sprintf "/#add/%i/%i" a b
          location.assign newUrl
        | _ -> ()
      | _ -> ()
    | _ -> ()

  createApp { CurrentRoute = None; ValueA = 0; ValueB = 0 } view update
  |> withStartNodeSelector "#app"
  |> withProducer navigationOnChangeProducer
  //|> withProducer (fun h -> navigationPushAgent.Post(AddHandler h))
  |> withSubscriber "navigation-subscriber" navigationSubscriber
  |> start renderer
  |> ignore