Some tuning:
- finite now uses rev_append (tail recursive!) to append stopper, because @
needs to much stack space for large strings
- repeat is now tail recursive
consts norm :: ifex => ifex
primrec
"norm (CIF b) = CIF b"
"norm (VIF x) = VIF x"
"norm (IF b t e) = normif b (norm t) (norm e)"