Macro processing language
https://www.gnu.org/software/m4 This formula is keg-only.

Current version

m4 requires the following formula to be installed:
xz 5.2.3 General-purpose data compression with high compression ratio

Recent formula history

Mike McQuaid m4: use *_by_macos.
JCount m4: %n crash fix for 10.13
ilovezfs m4: swap GNU url and mirror.
Mike McQuaid m4: import homebrew/dupes into core.

Formula code at GitHub