Concatenates two parameter lists into one. Each parameter list can be either a single type, or a tuple.
The arity of a type if 0 if it's Unit/Nothing, as these types act as a neutral element in the tuple-concatenation operation that
takes place when combining inputs/outputs.
The arity of a type is 1 if it's a "singular" type (as viewed at compile-time; at run-time, the value might in fact be a tuple).
Otherwise, the arity of a tuple.
- Companion:
- object