= {
    list   = " , ",
    label  = "' = ",
    lambda = "\ . ",
    apply  = "  ",
  },
  precedence = { {"list"},{"label"},{"lambda"},{"apply"} },
}  
function parser:number(value)      return tonumber(value) end
function parser:variable(value)    return value end
function parser:label(name, def)   return Label{ name = name, def = def } end
function parser:lambda(args, body) return Lambda{ args = args, body = body } end
function parser:apply(func, args)  return Apply{ func = func, args = args } end
funct