Emoji is just Unicode, so putting "I :heart: you" instead of "I ❤️ you" in a Unicode text file is rather, shall we say, na:LATIN SMALL LETTER I WITH DIAERESIS:ve -- this shit belongs in the editor. As implemented by, for example and in no particular order: https://github.com/junegunn/vim-emoji, https://github.com/kyuhi/vim-emoji-complete, https://github.com/mattn/emoji-vim, https://github.com/rhysd/github-complete.vim.

On the command line, the command line is the editor, so this program makes a lot of sense!