doc-src/Tutorial/CodeGen/exec

use Library.Some/None instead of just Some/None in generated quickcheck code

consts exec :: ('a => 'v) => 'v list => (('a,'v) instr) list => 'v list
primrec
"exec s vs [] = vs"
"exec s vs (i#is) = (case i of
    Const v  => exec s (v#vs) is
  | Load a   => exec s ((s a)#vs) is
  | Apply f  => exec s ( (f (hd vs) (hd(tl vs)))#(tl(tl vs)) ) is)"