ParamObject on delegate function

[joprice]

When writing bindings for something like a hook that returns a function, where the returned function takes a params object, it would be convenient to be able to define a delegate that uses ParamObject:

[<ParamObject(1)>]
type NavigateFunction = delegate of to_: string * ?replace: bool * ?state: obj option

[<Import("useNavigate", "react-router")>]
let useNavigate () : NavigateFunction = nativeOnly

The alternative is using a type with Emit("$0($1...)")

type NavigateFunction =
    [<Emit("$0($1...)"); ParamObject(1)>]
    abstract Invoke:
      to_: string *
      ?replace: bool *
      ?state: obj option ->
        unit

(Maybe the second one could also be made prettier and less error prone to type with an EmitApply or EmitCall helper?)

[MangelMaxime]

Could you please share the JavaScript/TypeScript code which is trying to be mapped by this code?

[joprice]

https://unpkg.com/browse/[email protected]/dist/development/index.d.ts

interface NavigateFunction {
  (to: To, options?: NavigateOptions): void | Promise<void>;
  (delta: number): void | Promise<void>;
 }

declare function useNavigate(): NavigateFunction;

Also, just found this convenient interface for looking up the types for a lib https://types.kubajastrz.com/

[MangelMaxime]

The other alternative is to not use ParamObject but instead something closer to the TypeScript API:

This is what Glutinum generates right now:

[<AbstractClass>]
[<Erase>]
type Exports =
    [<Import("useNavigate", "REPLACE_ME_WITH_MODULE_NAME")>]
    static member useNavigate () : NavigateFunction = nativeOnly

[<AllowNullLiteral>]
[<Interface>]
type NavigateFunction =
    [<Emit("$0($1...)")>]
    abstract member Invoke: ``to``: To * ?options: NavigateOptions -> U2<unit, JS.Promise<unit>>
    [<Emit("$0($1...)")>]
    abstract member Invoke: delta: float -> U2<unit, JS.Promise<unit>>

In a ideal world NavigateOptions would be generated as a ParamObject so you would end up writing:

useNavigate.Invoke("to-somewhere", NavigateOptions(
    replace = true
  )
)

when in TypeScript you would write

useNavigate("to-somewhere", {
  replace: true
})

You could perhaps optimise it even more by generating something like that

⚠️ not tested

[<AbstractClass>]
[<Erase>]
type Exports =
    [<Emit("$0($1...)")>]
    [<Import("useNavigate", "REPLACE_ME_WITH_MODULE_NAME")>]
    abstract member Invoke: ``to``: To * ?options: NavigateOptions -> U2<unit, JS.Promise<unit>>
    [<Emit("$0($1...)")>]
    [<Import("useNavigate", "REPLACE_ME_WITH_MODULE_NAME")>]
    abstract member Invoke: delta: float -> U2<unit, JS.Promise<unit>>