String substitution language, a more general macro facility than the C preprocessor, first really publicised as the '''macro''' processor for [Ratfor] in the book [Software Tools]. It's a sophisticated language, but tricky to use because there's no unique substitution symbol to distinguish macros from ordinary running text.

[DKF]: It's Turing-Complete, but only really used for [autoconf] hacking now (and that's a fairly heavily modified version).

[Peter da Silva]: It's also used in sendmail for automating the generation of config files.

Back around '82, after I left Berkeley, I was using RSX-11 and feeling UNIX-starved. I took a copy of [Software Tools] and implemented everything in it from '''Ratfor''' through '''ed'''. When I implemented '''macro''' I renamed all the internal symbols so they began with a dollar sign. This made a huge difference in the usability of the language.

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[LV] So, are there enough benefits to m4 to make it worth a developer's time to use it
with Tcl to write sort of metacode, which would be expanded before execution?
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[Category Language]