samer@0: function o=bindcat(X,F,varargin)
samer@0: % bindcat - sort of monadic bind for sequences.
samer@0: %
samer@0: % bindcat ::
samer@0: %    data A				~ 'the first sequence',
samer@0: %	  (data A->data A)~ 'function to return second sequence given last element of first'
samer@0: % -> data A          ~ 'resultant sequence'.
samer@0: %
samer@0: % The resulting sequence consists of the entire sequence represented by the
samer@0: % first parameter, followed by the sequence obtained by applying the second
samer@0: % parameter to the last nonempty element of the first sequence. 
samer@0: %
samer@0: % Example:
samer@0: %
samer@0: %    gather(2,bindcat(celldata({1,2,3,4}),@(x)take(head(x),0)))
samer@0: %
samer@0: % ans = 1  2  3  4  0  0  0  0
samer@0: 
samer@0: 
samer@0: if nargin==0, o=bindcat(0,@id); 
samer@0: elseif nargin==1 && isa(sources,'bindcat'), o=elems;
samer@0: else
samer@0: 	if isempty(X), o=F(X); % degenerate case
samer@0: 	else
samer@0: 		o.nfn=F;
samer@0: 		o=class(o,'bindcat',ddata(X,size(X), ...
samer@0: 			'datafn',@datafn,'charfn',@stringfn,'nextfn',@nextfn, ...
samer@0: 			varargin{:}));
samer@0: 	end
samer@0: end
samer@0: 
samer@0: 
samer@0: function x=datafn(o), x=headsource(o);
samer@0: function s=stringfn(o), s=sprintf('%s >>= %s',tostring(source(o)),char(o.nfn));
samer@0: function o1=nextfn(o),
samer@0: 	o1=next_c(o); 
samer@0: 	if isempty(o1), o1=o.nfn(source(o)); end
samer@0: 	
samer@0: 		
samer@0: 
samer@0: