It’s common in the OpenStreetMap ecosystem, because an embedded scripting language is really the best way to regularise OSM’s tag soup. osm2pgsql (as used here)

It’s common in the OpenStreetMap ecosystem, because an embedded scripting language is really the best way to regularise OSM’s tag soup. osm2pgsql (as used here), OSRM, and tilemaker all use it in broadly similar ways.