initialise app with a file path, for the functionality of loading different files from the terminal

imperative-shell/init-glfw.sml

@@ -2,7 +2,7 @@ structure InitGlfw =
 struct
   open CML
 
-  fun init () =
+  fun init path () =
     let
       (* Set up GLFW. *)
       val _ = Glfw.init ()
@@ -20,6 +20,7 @@ struct
         , Constants.windowHeight
         , Constants.initialWidthClickPoints
         , Constants.initialHeightClickPoints
+        , path
         )
 
       val graphLines = GraphLines.generate initialModel
@@ -59,6 +60,6 @@ struct
       ()
     end
 
-  fun main () =
-    (RunCML.doit (init, NONE); ())
+  fun main path =
+    (RunCML.doit (init path, NONE); ())
 end

imperative-shell/shell.sml

@@ -3,7 +3,8 @@ struct
   fun main () =
     case CommandLine.arguments () of
       ["-r"] => Converter.main ()
-    | [] => InitGlfw.main ()
+    | [filename] => InitGlfw.main filename
+    | [] => print "error: no arguments\n"
     | args =>
         let
           val args = String.concatWith "" args