So I'm on mac right now. I see some videos about making functions. But the tutorials only show it being used in notepad ++. I tried it in TextEdit (A text application) but I couldn't make one of those files. It won't run, even after I did everything. I'm still asking if there is an easy way to make one of those files. But no one has an answer. So my suggestion would be to allow MAC users to create .mcfunction files too.
Apple's textEdit app will edit .mcfunction files just fine. just make sure it is plain text. To do this, go to Format > Make Plain Text in menu. If you don't then the file is Rich Text not plain text.
Alternatively, I would recommend free code editor Sublime Text. The cool thing about Sublime Text is that a AjaxGb created a language library for mcfunctions it offers syntax highlighting and error hinting. Its even a little better than similar options for Notepad++.