[Joker_vD]

Because there is a lot of additional stuff you may want to add to a node at the later stages of translation, not only the type field: you may also want a usage count, reference from usages, reference to the defining function, global/local value numbers, "can be an immediate in an instruction/requires load from constant pool" flags, the allocated register, the allocated spill slot, etc. Surely you don't put all of that backend-specific (or even single-pass specific) stuff into a supposedly generic AST node that your frontend produces?