Proposed arity type trait

gistfile1.txt

#---evals.nim---

proc evalTypeTrait*(trait, operand: PNode, context: PSym): PNode =
  InternalAssert operand.kind == nkSym

  let typ = operand.sym.typ.skipTypes({tyTypeDesc})
  case trait.sym.name.s.normalize
  of "name":
    result = newStrNode(nkStrLit, typ.typeToString(preferName))
    result.typ = newType(tyString, context)
    result.info = trait.info
  of "arity":    
    result = newIntNode(nkIntLit, typ.n.len)
    result.typ = newType(tyInt, context)
    result.info = trait.info
  else:
    internalAssert false


#---typetraits.nim---

proc arity*(t: typedesc): int {.magic: "TypeTrait".}
  ## Returns the arity of the given type