#load "q_MLast.cmo";;
#load "pa_extend.cmo";;
 
open Pcaml;;
 
EXTEND
expr: LEVEL "simple"
[
[ "++"; v = expr -> <:expr< do { incr $v$; $v$.val } >> ]
| [ v = expr; "++" -> <:expr< let o = $v$.val in do { incr $v$; o } >> ]
];
END;;