fun exec_prepared(stmt: String, nParams: Int, values: Array[String], pLengths: Array[Int], pFormats: Array[Int], resultFormat: Int): NativePGResult import String.to_cstring, Array[String].[], Array[Int].[] `{
    const char * stmtName = String_to_cstring(stmt);
    const char * paramValues[nParams];
    int paramLengths[nParams];
    int paramFormats[nParams];
    int i;
    for(i = 0; i < nParams; i++)
      paramValues[i] = String_to_cstring(Array_of_String__index(values, i));
    for(i = 0; i < nParams; i++)
      paramLengths[i] = Array_of_Int__index(pLengths, i);
    for(i = 0; i < nParams; i++)
      paramFormats[i] = Array_of_Int__index(pFormats, i);
    PGresult * res = PQexecPrepared(self, stmtName, nParams, paramValues, paramLengths, paramFormats, resultFormat);
    return res;
  `}