[mynegation]

I like the idea of using the language (golang) itself to write the rules, instead of DSL or specialized language like Datalog. But why go for a restricted ad hoc interpretation instead of just executing this code as a plugin?

[quasilyte]

Mostly because plugins support in Go is not ideal and it still requires compilation (in plugin mode).

I believe Daniel Martí plans to make gogrep usable as a library, so it will be possible to write such Go programs in the future.