-- Converting peano representation of natural nubmer
-- (e.g., S(S(Z))) to LSB representation 
-- (e.g., [B0,B1]).

peano2bin(x)  = testHalve( halve(x) )


testHalve( Pair(b,Z)   ) = Cons(b,Nil)
testHalve( Pair(b,S(x))) = Cons(b,peano2bin(S(x)))				

halve(Z)       = Pair(B0,Z)
halve(S(Z))    = Pair(B1,Z)
halve(S(S(x))) = let Pair(b,s) = halve(x)
	         in  Pair(b,S(s))