-- Solutions to exercises from the Central European Functional Programming summer school
-- July 4th-16th 2005

-- Write a Hume program to select between one of two inputs taken from separate files
-- depending on the value of a third input;

-- HW-Hume solution

-- Note 
--  a) the test generator box with no input;
--  b) the fair matches in testgen and select; and
--  c) the final case in select, which sends the box into a loop at end of input.

-- Kevin Hammond, 5th July 2005


program

 data LR = Left | Right;

 box testgen in ()
 out (control :: LR)
 fair
     * -> Left
   | * -> Right;

 box select
 in (cin1,cin2::char, control :: LR)
 out (cout::char)
 fair
    (c,*,Left)  -> c
  | (*,c,Right) -> c
  | (*,*,_) -> *;

 stream stdout to "std_out";

 stream sel1 from "selects1.txt";
 stream sel2 from "selects2.txt";

 wire select (sel1,sel2,testgen.control)
             (stdout);

 wire testgen () (select.control);