function s=dropwhile(f,s)
% drop - Drop elements of sequence that satisfy condition 
%
% drop :: (A->bool), seq A -> seq A

% if isempty(s) return s; end
x=head(s);
while f(x), 
	s=next(s); 
	if isempty(s), break; end
	x=head(s); 
end
	

