例: Pascal のような repeat until

camlp4_pascal_repeat.txt

### http://www.jmuk.org/~mukai/camlp4tut.html#label-94
$ cat foo.ml
open Camlp4.PreCast
open Syntax
EXTEND Gram
  GLOBAL: expr;

  expr: LEVEL "top"
    [[ "repeat"; e1 = expr; "until"; e2 = expr ->
          <:expr< do { $e1$; while not $e2$ do { $e1$; } } >> ]];
END;;
$ cat bar.ml
let main () =
  let i = ref 0 in
  repeat print_int !i; incr i until !i = 10;
  print_newline ()
let _ = main ()
$ cat make.sh
#!/bin/sh
rm -f *.cmi *.cmo
ocamlc -pp "camlp4o pa_extend.cmo q_MLast.cmo" -I +camlp4 -c foo.ml
ocamlc -pp "camlp4o foo.cmo" bar.ml
$ ./make.sh
$ ./a.out
0123456789