:- module termination.

:- interface.
:- import_module char, list.

% no problem if this is commented out and --infer-all enabled
:- pred tokenizable(list(char)::in) is semidet.


:- implementation.
:- import_module string.

tokenizable(Line) :-
	(Line = [], true;
	 identifier(_, Line, Line1), tokenizable(Line1)).

:- pred is_digit_term(char::in) is semidet.
% this pragma behaves as expected (try commenting out)
:- pragma terminates(is_digit_term/1).
is_digit_term(C) :- is_digit(C).

:- func from_char_list_term(list(char)) = string.
:- pragma terminates(from_char_list_term/1).
% this triggers the "termination constant of infinity" warnings
from_char_list_term(L) = from_char_list(L).
% this does not
%from_char_list_term(L) = "X".

:- pred identifier(string::out, list(char)::in, list(char)::out) is semidet.
identifier(from_char_list_term([C])) --> [C], { is_digit_term(C) }.