Parsing is done line by line so don't define a programm rule

parser.mly

@@ -23,10 +23,6 @@
 
 %%
 
-prog:   /* empty */  { [] }
-      | line prog    { $1 :: $2 }
-;
-
 line:   TYPE CID DEF ty DOT           { ($1, Typedef (Cid ($2), $4)) }
       | VAR ID COLUMN ty DEF term DOT { ($1, Vardef (Id ($2), $4, $6)) }
       | CHECK term COLUMN ty DOT      { ($1, Check ($2, $4)) }