package ast

import (
  "fmt"
  "strings"
)

type AST struct {
  Tag Tag
  Val interface{}
}

type Tag int8

const (
  Symbol Tag = iota
  List
  String
  Num
  Bool
)

func (tag Tag) String() string {
    names := []string{
        "Symbol",
        "List",
        "String",
        "Num",
        "Bool",
    }

    return names[tag]
}

func (ast AST) Pretty() string {
  if ast.Tag == List {
    var agg []string
    for _, elem := range(ast.Val.([]AST)) {
      agg = append(agg, elem.Pretty())
    }
    return "(" + strings.Join(agg, " ") + ")"
  }
  return fmt.Sprintf("%v", ast.Val)
}