Are Vim script solutions that does not print the output but starts a vim session with output legal?

Question

I wrote this answer in this challenge using Vim script. I think I was really creative and got very proud of my solution.

But I am not so sure if this is legal because this program does not print its output to stdout but opens a Vim session with the output of the program.

This command will run the Vim script program I posted:

$ echo "This is a test line!" | vim - -c 'nm Q vEUWvEuWQ|norm Q'

This will open up Vim displaying this:

THIS is A test LINE!
~
~
~
~
~

I personally think that this is legal because it does display the correct solution but I am not sure if it counts because the result is displayed within Vim and not printed to stdout.

I am new to codegolf so I would like to hear from you if I can post more solutions like this to other programs.

Answer 1

I would personally consider it valid. However, when in doubt, you should always ask the question writer by commenting on the question. Although there are set defaults for inputs and output formats, what the question writer says will overwrite these defaults.