Update idris-compile-and-execute for Idris2

Backport of idris2-compile-and-execute from https://github.com/idris-community/idris2-mode/pull/20/files
with preserving backward compatibility for Idris 1

Co-authored-by: "G. Allais" <guillaume.allais@ens-lyon.org>

idris-commands.el

@@ -748,12 +748,15 @@ Otherwise, case split as a pattern variable."
                        ;; make sure point is at new defn
                        (goto-char end)))))))))))
 
-
 (defun idris-compile-and-execute ()
-  "Execute the program in the current buffer"
+  "Execute the program in the current buffer."
   (interactive)
   (idris-load-file-sync)
-  (idris-eval '(:interpret ":exec")))
+  (if (>=-protocol-version 2 1)
+      (let ((name (read-string "MExpression to compile & execute (default main): "
+                                     nil nil "main")))
+        (idris-repl-eval-string (format ":exec %s" name) 0))
+    (idris-eval '(:interpret ":exec"))))
 
 (defvar-local proof-region-start nil
   "The start position of the last proof region.")