anytype.nim

type
  AnyTypeTypes = enum
    ATString, ATInt, ATBool
  AnyType = object
    case kind: AnyTypeTypes
    of ATString: str: string
    of ATInt: n: int
    of ATBool: b: bool

proc wrap(str: string): AnyType = result.kind = ATString; result.str = str
proc wrap(n: int): AnyType = result.kind = ATInt; result.n = n
proc wrap(b: bool): AnyType = result.kind = ATBool; result.b = b

proc whatis(x: AnyType) =
  case x.kind
  of ATString: echo "it's a string: " & x.str
  of ATInt: echo "it's a string: " & $x.n
  of ATBool: echo "it's a string: " & $x.b

whatis 42.wrap
whatis "hello".wrap