RosettaCodeData/Task/Mutual-recursion/Icon/mutual-recursion.icon

procedure main(arglist)
every write(F(!arglist))   # F of all arguments
end

procedure F(n)
if integer(n) >= 0 then
   return (n = 0, 1) |  n - M(F(n-1))
end

procedure M(n)
if integer(n) >= 0 then
   return (0 = n) | n - F(M(n-1))
end