I suggest to anyone considering M4 seriously to have a look at its substitution behaviour and syntax rules. Not only the default newline handling causes rules

I suggest to anyone considering M4 seriously to have a look at its substitution behaviour and syntax rules. Not only the default newline handling causes rules to become cluttered the more complex your macros get but the resubstitution of already parsed tokens recursively and the quoting that needs to be considered to avoid this can cause surprises - specially as the number of macros grows bigger. Maybe for config files or configuring source files m4 is great, but for anything more complex that need to be easier to read and understood, I'd avoid m4.