Core Erlang Metaprogramming example

transform.erl

-module(transform).
-export([main/1]).

main(File) ->
  case compile:file(File, [to_core, binary, no_copt]) of
    {ok, ModuleName, CoreForms} ->
        TransForms = cerl_trees:map(fun replace_concat/1, CoreForms),
        CoreName = atom_to_list(ModuleName) ++ ".core",
        file:write_file(CoreName,
                        cerl_prettypr:format(TransForms));
    _ ->
      io:fwrite("Error: Could not compile file.~n"),
      exit(file_error)
  end.

replace_concat(Node) ->
  case cerl:type(Node) of
    call ->
      ConcCallName = cerl:concrete(cerl:call_name(Node)),
      case ConcCallName of
        '++' ->
          [FstArg, SndArg] = cerl:call_args(Node),
          FlatFstArg = cerl:cons_hd(FstArg),
          cerl:c_cons(FlatFstArg,
                      SndArg);
        _ -> Node
      end;
    _ -> Node
  end.