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% sets.ml (c) R.J.Boulton 1990 %
%----------------------------------------------------------------------------%
% Function to determine whether a list contains any repetitions %
letrec no_rep l =
% : (* list -> bool) %
if (null l)
then true
else if (mem (hd l) (tl l))
then false
else no_rep (tl l);;
% Function to remove any repetitions in a list %
letrec remove_rep l =
% : (* list -> * list) %
if (null l)
then []
else if (mem (hd l) (tl l))
then (remove_rep (tl l))
else (hd l).(remove_rep (tl l));;
% Function to determine if one list (containing no repetitions) is a %
% subset of another list (containing no repetitions). %
% The function tests if subl is a subset of l by subtracting (setwise) l %
% from subl. If this gives a null list, then subl is a subset of l. %
let is_subset l subl = null (subtract subl l);;
% : (* list -> * list -> bool) %
%----------------------------------------------------------------------------%
|
