diff --git a/hipo4/bank.cpp b/hipo4/bank.cpp
index abb4bd2..9d54a92 100644
--- a/hipo4/bank.cpp
+++ b/hipo4/bank.cpp
@@ -362,13 +362,13 @@ void bank::rowlist::setList(list_t list) {
   m_init = true;
 }
 
-void bank::rowlist::reduce(std::function<double(bank&, int)> func) {
+void bank::rowlist::reduce(std::function<bool(bank&, int)> func) {
   if(ownerBankIsUnknown("reduce"))
     return;
   auto indx = m_list;
   m_list.clear();
   for(auto const& r : indx)
-    if(func(*m_owner_bank, r) > 0.5)
+    if(func(*m_owner_bank, r) == true)
       m_list.push_back(r);
 }
 
@@ -376,9 +376,9 @@ void bank::rowlist::reduce(const char *expression) {
   if(ownerBankIsUnknown("reduce"))
     return;
   Parser p(expression);
-  int nitems = m_owner_bank->getSchema().getEntries();
+  int nitems     = m_owner_bank->getSchema().getEntries();
   schema &schema = m_owner_bank->getSchema();
-  auto indx = m_list;
+  auto indx      = m_list;
   m_list.clear();
   for(auto const& r : indx){
     for(int i = 0; i < nitems; i++)
@@ -388,16 +388,11 @@ void bank::rowlist::reduce(const char *expression) {
   }
 }
 
-bank::rowlist::list_t bank::rowlist::s_number_list_init(list_t::size_type num) {
-  list_t result;
-  for(list_t::size_type i = 0; i < num; i++)
-    result.push_back(i);
-  return result;
-}
-
-bank::rowlist::list_t bank::rowlist::getFullList(list_t::size_type num) {
-  if(num < 0)
+bank::rowlist::list_t bank::rowlist::getFullList(int num) {
+  if(num < 0) {
+    std::cerr << "ERROR: attempted to call rowlist::getFullRowList with a negative size" << std::endl;
     return {};
+  }
   if(num <= s_number_list.size())
     return list_t(s_number_list.begin(), s_number_list.begin() + num);
   else {
@@ -408,8 +403,6 @@ bank::rowlist::list_t bank::rowlist::getFullList(list_t::size_type num) {
   }
 }
 
-bank::rowlist::list_t bank::rowlist::s_number_list = bank::rowlist::s_number_list_init();
-
 bool bank::rowlist::ownerBankIsUnknown(std::string_view caller) {
   if(m_owner_bank == nullptr) {
     std::cerr <<
@@ -422,6 +415,15 @@ bool bank::rowlist::ownerBankIsUnknown(std::string_view caller) {
   return false;
 }
 
+bank::rowlist::list_t bank::rowlist::s_number_list_init(list_t::size_type num) {
+  list_t result;
+  for(list_t::size_type i = 0; i < num; i++)
+    result.push_back(i);
+  return result;
+}
+
+bank::rowlist::list_t bank::rowlist::s_number_list = bank::rowlist::s_number_list_init();
+
 
 //////////////////////////////////////////////////////////////////////////////////
 // hipo::bank
diff --git a/hipo4/bank.h b/hipo4/bank.h
index c887255..a8caf15 100644
--- a/hipo4/bank.h
+++ b/hipo4/bank.h
@@ -230,15 +230,15 @@ namespace hipo {
 
         /// filter the list according to a function
         /// @param func a function which takes a `hipo::bank` reference and an `int` row number and returns a `double`;
-        /// if the returned `double` is larger than 0.5, the row is accepted
-        void reduce(std::function<double(bank&, int)> func);
+        /// if the returned `bool` is `true`, the row is accepted
+        void reduce(std::function<bool(bank&, int)> func);
         /// filter the list according to an expression
         /// @param expression the filter expression
         void reduce(char const* expression);
 
         /// @returns a list of numbers from 0 to `num`
         /// @param num the size of the list
-        static list_t getFullList(list_t::size_type num);
+        static list_t getFullList(int num);
 
         /// @param ownerBank set the owner bank
         void setOwnerBank(bank* const ownerBank) { m_owner_bank = ownerBank; }