I'm sad that M4 is getting a bad reputation; probably it is more due to lack of knowledge than the actual tool, because the language is really simple. As usual,

I'm sad that M4 is getting a bad reputation; probably it is more due to lack of knowledge than the actual tool, because the language is really simple. As usual, many devs would copy/paste m4 macros without understanding what is going on. Also, heavy use by Sendmail or SELinux didn't add to reputation either (again, not due M4 itself). But I find M4 a true gem "no one heard of" - a portable macro processor you can use with basically anything involved with the plain text. Especially it is useful where you have tons of boilerplate code to type (Java, Ansible, Go, js/html/css to name a few).