declare
[File]={Module.link ['File.ozf']}
local
   fun {Tokenize Source}
      try
     {TokenizeHelper {Sanitize Source}}
      catch E then
     {String.toAtom {Append E " must start with a lowercase letter."}}
      end
   end

   fun {TokenizeHelper Source}
      case Source
      of nil then nil
      [] H|T then
     if {String.isInt H} then {String.toInt H}|{TokenizeHelper T}
     elseif {String.isFloat H} then {String.toFloat H}|{TokenizeHelper T}
     elseif {Char.isUpper H.1} then raise H end
     elseif {Char.isDigit H.1} then raise H end
     else {String.toAtom H}|{TokenizeHelper T}
     end
      end
   end

   fun {Sanitize Source}
      {String.tokens {RemoveExtraSpaces {SpaceEverything Source} 0} & }
   end

   fun {SpaceEverything Source}
      case Source
      of nil then nil
      [] &\r|T then {SpaceEverything T}
      [] &\n|T then & |{SpaceEverything T}
      [] &\t|T then & |{SpaceEverything T}
      [] &,|T then & |&,|& |{SpaceEverything T}
      [] &SEMI>|T then & |&SEMI>|& |{SpaceEverything T}
      [] &{|T then & |&{|& |{SpaceEverything T}
      [] &}|T then & |&}|& |{SpaceEverything T}
      [] &(|T then & |&(|& |{SpaceEverything T}
      [] &)|T then & |&)|& |{SpaceEverything T}
      [] &*|T then & |&*|& |{SpaceEverything T}
      [] &/|T then & |&/|& |{SpaceEverything T}
      [] &+|T then & |&+|& |{SpaceEverything T}
      [] &-|T then & |&-|& |{SpaceEverything T}
      [] &!|&=|T then & |&!|&=|& |{SpaceEverything T}
      [] &<|&=|T then & |&<|&=|& |{SpaceEverything T}
      [] &=|&=|T then & |&=|&=|& |{SpaceEverything T}
      [] &>|&=|T then & |&>|&=|& |{SpaceEverything T}
      [] &=|T then & |&=|& |{SpaceEverything T}
      [] &<|T then & |&<|& |{SpaceEverything T}
      [] &>|T then & |&>|& |{SpaceEverything T}
      [] H|T then H|{SpaceEverything T}
      end
   end

   fun {RemoveExtraSpaces Source SpacesMode}
      case Source
      of nil then nil
      [] & |T then
     if SpacesMode == 0 then & |{RemoveExtraSpaces T 1}
     else {RemoveExtraSpaces T 1}
     end
      [] H|T then H|{RemoveExtraSpaces T 0}
      end
   end
in
   fun {Tokenizer Source}
      {Tokenize Source}
   end
end
Content = {File.readList "foo.txt"}
{Browse {Tokenizer Content}}