feat: introduce config and persistent rendering mode

examples/list/dune

@@ -1,3 +1,3 @@
 (executable
-  (name main)
-  (libraries minttea spices leaves str))
+ (name main)
+ (libraries minttea spices leaves str))

minttea/config.ml

@@ -0,0 +1 @@
+type t = { render_mode : [ `clear | `persist ]; fps : int }

minttea/minttea.ml

@@ -3,21 +3,23 @@ module Event = Event
 module Command = Command
 module App = App
 module Program = Program
+module Config = Config
 
+let config ?(render_mode = `clear) ?(fps = 60) () = Config.{ render_mode; fps }
 let app = App.make
 
-let run ?(fps = 60) ~initial_model app =
-  let prog = Program.make ~app ~fps in
+let run ?(config = config ()) ~initial_model app =
+  let prog = Program.make ~app ~config in
   Program.run prog initial_model;
   Logger.trace (fun f -> f "terminating")
 
-let start app ~initial_model =
+let start ?(config = config ()) app ~initial_model =
   let module App = struct
     let start () =
       Logger.set_log_level None;
       let pid =
         spawn_link (fun () ->
-            run app ~initial_model;
+            run ~config app ~initial_model;
             Logger.trace (fun f -> f "about to shutdown");
             shutdown ~status:0 ())
       in

minttea/minttea.mli

@@ -1,5 +1,11 @@
 open Riot
 
+module Config : sig
+  type t
+end
+
+val config : ?render_mode:[ `clear | `persist ] -> ?fps:int -> unit -> Config.t
+
 module Event : sig
   type modifier = No_modifier | Ctrl
 
@@ -46,5 +52,5 @@ val app :
   unit ->
   'model App.t
 
-val run : ?fps:int -> initial_model:'model -> 'model App.t -> unit
-val start : 'model App.t -> initial_model:'model -> unit
+val run : ?config:Config.t -> initial_model:'model -> 'model App.t -> unit
+val start : ?config:Config.t -> 'model App.t -> initial_model:'model -> unit

minttea/program.ml

@@ -1,9 +1,9 @@
 open Riot
 
 type Message.t += Timer of unit Ref.t | Shutdown
-type 'model t = { app : 'model App.t; fps : int }
+type 'model t = { app : 'model App.t; config : Config.t }
 
-let make ~app ~fps = { app; fps }
+let make ~app ~config = { app; config }
 
 exception Exit
 
@@ -55,14 +55,14 @@ let init { app; _ } initial_model renderer =
   Renderer.render renderer view;
   loop renderer app initial_model
 
-let run ({ fps; _ } as t) initial_model =
+let run ({ config; _ } as t) initial_model =
   Printexc.record_backtrace true;
   let renderer =
     spawn (fun () ->
         (* NOTE(@leostera): reintroduce this when riot brings back process-stealing *)
         (* process_flag (Priority High); *)
         let runner = Process.await_name "Minttea.runner" in
-        Renderer.run ~fps ~runner)
+        Renderer.run ~config ~runner)
   in
   let runner =
     spawn (fun () ->

minttea/renderer.ml

@@ -14,6 +14,7 @@ type t = {
   ticker : Timer.timer;
   width : int;
   height : int;
+  render_mode : [ `clear | `persist ];
   mutable buffer : string;
   mutable last_render : string;
   mutable lines_rendered : int;
@@ -61,7 +62,7 @@ and flush t =
   let new_lines_this_flush = List.length new_lines in
 
   (* clean last rendered lines *)
-  if t.lines_rendered > 0 then
+  if t.render_mode = `clear && t.lines_rendered > 0 then
     for _i = 1 to t.lines_rendered - 1 do
       Terminal.clear_line ();
       Terminal.cursor_up 1
@@ -107,7 +108,8 @@ let max_fps = 120
 let cap fps = Int.max 1 (Int.min fps max_fps) |> Int.to_float
 let fps_to_float fps = 1. /. cap fps *. 1_000. |> Int64.of_float
 
-let run ~fps ~runner =
+let run ~config ~runner =
+  let Config.{ render_mode; fps } = config in
   let ticker =
     Riot.Timer.send_interval ~every:(fps_to_float fps) (self ()) Tick
     |> Result.get_ok
@@ -123,6 +125,7 @@ let run ~fps ~runner =
       is_altscreen_active = false;
       lines_rendered = 0;
       cursor_visibility = `visible;
+      render_mode;
     }
 
 let render pid output = send pid (Render output)

minttea/renderer.mli

@@ -1,6 +1,6 @@
 open Riot
 
-val run : fps:int -> runner:Pid.t -> unit
+val run : config:Config.t -> runner:Pid.t -> unit
 val render : Pid.t -> string -> unit
 val enter_alt_screen : Pid.t -> unit
 val exit_alt_screen : Pid.t -> unit