Ch4, Ex9

declare GateMaker
fun {GateMaker F}
   fun {$ Xs Ys}
      fun {GateLoop Xs Ys}
         case Xs#Ys of (X|Xr)#(Y|Yr) then
            {F X Y}|{GateLoop Xr Yr}
         end
      end
   in
      thread {GateLoop Xs Ys} end
   end
end

declare AndG OrG NandG NorG XorG
AndG ={GateMaker fun {$ X Y} X*Y end}
OrG ={GateMaker  fun {$ X Y} X+Y-X*Y end}
NandG={GateMaker fun {$ X Y} 1-X*Y end}
NorG ={GateMaker fun {$ X Y} 1-X-Y+X*Y end}
XorG ={GateMaker fun {$ X Y} X+Y-2*X*Y end}

declare FullAdder
proc {FullAdder X Y Z ?C ?S}
   K L M
in
   K={AndG X Y}
   L={AndG Y Z}
   M={AndG X Z}
   C={OrG K {OrG L M}}
   S={XorG Z {XorG X Y}}
end

% A number is represented by x0|x1|x2|...xn|_ 
% where x0 is lowest order bit while xn is
% that of highest order
declare BAdder %Binary Adder
local
   proc {SingleElemFullAdder X Y Z ?C ?S}
      L M in
      {FullAdder X|_ Y|_ Z|_ L M}
      C = L.1
      S = M.1
   end
   X Y
in
   fun {BAdder Xs Ys}
      fun {Adder Xs Ys C}
         case Xs#Ys of (X|Xr)#(Y|Yr) then Cnext S in
            {SingleElemFullAdder X Y C Cnext S}
            S|{Adder Xr Yr Cnext}
         end
      end
   in
      thread {Adder Xs Ys 0} end
   end
end

local
   X=1|1|0|_  % 3
   Y=0|0|1|_  % 4
in
   {Browse 'BAdder Test: 3+4: 1|1|1|_'}
   {Browse {BAdder X Y}}
end

local
   X=1|1|1|0|_  % 3
   Y=1|1|1|0|_  % 4
in
   {Browse 'BAdder Test: 7+7: 0|1|1|1|_'}
   {Browse {BAdder X Y}}
end