samer@3: function [Y,x]=spanc(f,x)
samer@3: % spanc - divide sequence using a test function
samer@3: %
samer@3: % spanc :: (A->bool), seq(A) -> {[N]->A}, seq(A).
samer@3: %
samer@3: % spanc f x = (seq2cell (takeWhile f x),dropWhile f x)
samer@3: % Will not terminate if head segments turns out to be infinite.
samer@3: %
samer@3: % Note: this is like span but returns a cell array for the head sequence
samer@3: 
samer@3: if isempty(x), Y={}; return
samer@3: else
samer@3: 	Y={};
samer@3: 	y=head(x);
samer@3: 	while f(y)
samer@3: 		Y=horzcat(Y,y);
samer@3: 		x=next(x);
samer@3: 		if isempty(x), break; end
samer@3: 		y=head(x);
samer@3: 	end
samer@3: end
samer@3: