with cursor movements, instead of passing in functions as parameters (callbacks/higher order functions), functorise the cursor movement functions instead so we can take advantage of defunctorisation and avoid the runtime cost of closures/higher order functions/function pointers

fcore/finish.sml

@@ -0,0 +1,37 @@
+structure Finish =
+struct
+  open AppType
+
+  fun buildTextAndClear (app: app_type, buffer, cursorIdx, searchList) =
+    let
+      val {windowWidth, windowHeight, startLine, searchString, ...} = app
+
+      (* move LineGap to first line displayed on screen 
+       * and move searchList to line's start idx as well *)
+      val buffer = LineGap.goToLine (startLine, buffer)
+
+      (* get new startLine which may move screen depending on cursor movements *)
+      val startLine = TextWindow.getStartLine
+        (buffer, startLine, cursorIdx, windowWidth, windowHeight)
+
+      (* move buffer to new startLine as required by TextBuilder.build *)
+      val buffer = LineGap.goToLine (startLine, buffer)
+      val lineIdx = TextBuilder.getLineAbsIdx (startLine, buffer)
+      val searchList = SearchList.goToNum (lineIdx, searchList)
+
+      val drawMsg = TextBuilder.build
+        ( startLine
+        , cursorIdx
+        , buffer
+        , windowWidth
+        , windowHeight
+        , searchList
+        , searchString
+        )
+
+      val mode = NORMAL_MODE ""
+    in
+      AppWith.bufferAndCursorIdx
+        (app, buffer, cursorIdx, mode, startLine, searchList, drawMsg)
+    end
+end