variants.nim

# This is an example how an abstract syntax tree could be modelled in Nim
type
  NodeKind = enum  # the different node types
    nkInt,          # a leaf with an integer value
    nkFloat,        # a leaf with a float value
    nkString,       # a leaf with a string value
    nkAdd,          # an addition
    nkSub,          # a subtraction
    nkIf            # an if statement
    
  Node = ref NodeObj
  NodeObj = object
    nodeId: int
    line, column: int
    case kind: NodeKind
    of nkInt:
      intVal: int
    of nkFloat:
      floatVal: float
    of nkString:
      strVal: string
    of nkAdd, nkSub:
      leftOp, rightOp: Node
    of nkIf:
      condition, thenPart, elsePart: Node