diff --git a/fzn-parser/flatzinc.y b/fzn-parser/flatzinc.y
index ae745fd..842f3f4 100644
--- a/fzn-parser/flatzinc.y
+++ b/fzn-parser/flatzinc.y
@@ -54,9 +54,6 @@
   // push the empty list
 #define NIL()   PUSH (("[]"))
 
-#define BINARY(op)      AST ("B,A", ("op(A,B)"))
-#define UNARY(op)       AST ("X",   ("op(X)"))
-
 %}
 
  
@@ -87,6 +84,7 @@ model          :                        { INIT ("[]"); }
                  var_decl_items         { AST ("X", ("vars(X)")); }
                  constraint_items       { AST ("X", ("constrs(X)")); }
                  model_end
+                 { AST ("S,C,V,P", ("fzn(P, V, C, S)")); }
 
 pred_decl_items : pred_decl_items pred_decl_item ';'   { CONS (); }
                 | pred_decl_items error ';'            { yyerrok; }
@@ -139,8 +137,8 @@ constraint_item:		/* -> [ constraint(...) | ] */
 constraint_elem:		/* -> [ CONSTR_ID, EXPRLIST | _ ] */
     IDENT '(' exprs ')'      { PUSH (("'%s'", $1)); }
 
-solve_item:
-    SOLVE annotations solve_kind
+solve_item:			/* -> [ solve(S,A) | _ ] */
+    SOLVE annotations solve_kind { AST ("S,A", ("solve(S, A)")); }
 
 solve_kind:
     SATISFY                  { PUSH (("satisfy")); }
@@ -163,7 +161,7 @@ pred_decl_arg:
    | ARRAY '[' pred_arg_array_index ']' OF  pred_arg_array_tail ':' IDENT
        { AST ("T,U,L", ("var(array(T,L,U)):'%s'", $8)); }
 
-pred_arg_array_index:
+pred_arg_array_index:		/* -> [ UB, LB | _ ] */
     INT                             { PUSH (("_,1")); }
   | INT_LITERAL DOTDOT INT_LITERAL  { PUSH (("%d,%d", $3, $1)); }
 
@@ -265,20 +263,24 @@ char* filename;
 
 int main(int argc, char *argv[])
 {
-    if (argc != 2) {
-        fprintf(stderr, "Usage: %s <file.fzn>\n", argv[0]);
-        exit(1);
-    }
-
+  if (argc == 1) {
+    yyin = stdin;
+  }
+  else if (argc == 2) {
     filename = argv[1];
     yyin = fopen(filename, "r");
     if (yyin == NULL) {
-        fprintf(stderr, "cannot open file: '%s'\n", filename);
-        exit(1);
+      fprintf(stderr, "cannot open file: '%s'\n", filename);
+      exit(1);
     }
-
-    yyparse();
-    return 0;
+  }
+  else {
+    fprintf(stderr, "Usage: %s [FILE.fzn]\n", argv[0]);
+    exit(1);
+  }
+
+  yyparse();
+  return 0;
 }
 
 int yyerror(char *s)
--
libgit2 0.21.2