add yank functionality in imperative shell

ffi/glfw-export.c

@@ -41,3 +41,8 @@ void swapBuffers(GLFWwindow *window) {
   glfwSwapBuffers(window);
 }
 
+void setClipboardString (GLFWwindow *window, const char *copyString) {
+  glfwSetClipboardString(window, copyString);
+  printf("ddone yanking");
+}
+

ffi/glfw-import.sml

@@ -22,4 +22,5 @@ struct
   val windowShouldClose = _import "windowShouldClose" public : window -> bool;
   val waitEvents = _import "waitEvents" public reentrant : unit -> unit;
   val swapBuffers = _import "swapBuffers" public : window -> unit;
+  val setClipboardString = _import "setClipboardString" public : window * string -> unit;
 end

message-types/draw-msg.sml

@@ -3,6 +3,7 @@ sig
   datatype t =
     REDRAW_TEXT of Real32.real vector
   | REDRAW_CURSOR of Real32.real vector
+  | YANK of string
 end
 
 structure DrawMsg :> DRAW_MSG =
@@ -10,4 +11,5 @@ struct
   datatype t =
     REDRAW_TEXT of Real32.real vector
   | REDRAW_CURSOR of Real32.real vector
+  | YANK of string
 end

shell/gl-draw.sml

@@ -164,6 +164,11 @@ struct
       ()
     end
 
+  fun yank (shellState: t, str) =
+    ( Glfw.setClipboardString (#window shellState, str);
+      shellState
+    )
+
   fun consumeDrawEvent (shellState, msg) =
     let
       val
@@ -178,6 +183,7 @@ struct
       case msg of
         REDRAW_TEXT textVec => uploadText (shellState, textVec)
       | REDRAW_CURSOR cursorVec => uploadCursor (shellState, cursorVec)
+      | YANK str => yank (shellState, str)
     end
 
   fun consumeDrawEvents (shellState as {drawMailbox, ...}: t) =