Circular lists

[Thomas Charles CONWAY]

Hi

With all this talk of circular lists, I thought people might be
interested/amused by the following.

Beware, it is a complete hack, but IMHO quite cute.

Enjoy,
Thomas
-- 
ZZ:wq!
^X^C
Thomas Conway               				      conway at cs.mu.oz.au
AD DEUM ET VINUM	  			      Every sword has two edges.

:- module inflist.

:- interface.

:- import_module list.

:- inst circular_list = bound([ground|circular_list]).

:- pred circularize(list(T), list(T)).
:- mode circularize(di(non_empty_list), out(circular_list)) is det.

:- implementation.

:- pragma c_code(circularize(A::di(non_empty_list), B::out(circular_list)), "
	B = A;
	while (field(mktag(1), A, 1) != 0)
		A = field(mktag(1), A, 1);

	field(mktag(1), A, 1) = B;
").