samer@0: % loop1 - Looping feedback arrow for stateful arrows.
samer@0: %
samer@0: % loop1 ::
samer@0: %    N:natural  ~'number of inputs for this arrow',
samer@0: %    M:natural  ~'number of outputs for this arrow',
samer@27: %    ({[N]->size} -> ([A@typelist(N), {S}] -> [B@typelist(M), {S}])) 
samer@0: %                           ~'function to map input sizes to state transformer',
samer@0: %    ({[N]->size} -> S0:S)  ~'function to map size of input to initial state'
samer@0: % -> arrow(A,B,S) ~'arrow from A to B with state of type S'.
samer@0: 
samer@0: function o=loop1(nin,nout,initfn)
samer@0: 	if nargin<1, 
samer@0: 		nin=1; nout=1;
samer@0: 		initfn=@(sz)deal(@(a,b)deal(a,b),[]); 
samer@0: 	end
samer@0: 	s.init=initfn; 
samer@0: 	s.nin=nin;
samer@0: 	s.nout=nout;
samer@0: 	o=class(s,'loop1',arrow(nin,nout));
samer@0: end
samer@0: