:- module write_canonical.

% synopsis: Shows the canonical output of a parsed term as defined by
%           various operators.

% author:   Douglas M. Auclair, DMA
% date:     January 5, 2006

:- interface.
:- import_module io, term.

:- pred write_canonical(term(T)::in, io::di, io::uo) is det.

:- implementation.
:- import_module list, string.

write_canonical(Term) -->
  { Term = functor(atom(Fn), List, _) } ->
    format("%s", [s(Fn)]),
    write_canonical_list(List)
  ;
  { Term = functor(integer(Int), _, _) } ->
    write(Int)
  ;
    write(Term).

:- pred write_canonical_list(list(term(T))::in, state::di, state::uo) is det.

write_canonical_list([]) --> [].
write_canonical_list([H|T]) -->
  print("("),
  write_canonical(H),
  write_canonical_list_aux(T),
  print(")").

:- pred write_canonical_list_aux(list(term(T)), state, state).
:- mode write_canonical_list_aux(in, di, uo) is det.

write_canonical_list_aux([]) --> [].
write_canonical_list_aux([H|T]) -->
  print(", "),
  write_canonical(H),
  write_canonical_list_aux(T).