Semantically, these say the same thing, so all of those concerns exist for “concat(a, b)” too. Avoiding having to parse the concat every time the line is invoke

Semantically, these say the same thing, so all of those concerns exist for “concat(a, b)” too. Avoiding having to parse the concat every time the line is invoked, avoiding having to apply runtime introspection to find out mapping between the variables and their locations, etc.