From 9f3a2fca44e0c4acc59c14972449a46bfad437c6 Mon Sep 17 00:00:00 2001
From: Emily Boudreaux <thomas@boudreauxmail.com>
Date: Mon, 9 Nov 2026 13:44:41 -0500
Subject: [PATCH] feat(utils/misc): added a number of misc things (e.g. float
 roundoff compensated summation class)

---
 .../serif/utils/misc/compensated_sum.hpp      | 21 +++++++++++++++++++
 .../serif/utils/misc/concepts/enumeration.hpp | 18 ----------------
 .../serif/utils/misc/concepts/exceptions.hpp  |  5 -----
 .../serif/utils/misc/concepts/numeric.hpp     |  6 ------
 .../utils/misc/traits/type_uniqueness.hpp     | 18 ++++++++--------
 5 files changed, 30 insertions(+), 38 deletions(-)
 create mode 100644 src/include/serif/utils/misc/compensated_sum.hpp
 delete mode 100644 src/include/serif/utils/misc/concepts/enumeration.hpp

diff --git a/src/include/serif/utils/misc/compensated_sum.hpp b/src/include/serif/utils/misc/compensated_sum.hpp
new file mode 100644
index 00000000..7c12dd86
--- /dev/null
+++ b/src/include/serif/utils/misc/compensated_sum.hpp
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <cmath>
+
+namespace serif::utils {
+    /// Neumaier summation retains small terms when a scalar reduction contains cancellation.
+    class CompensatedSum final {
+    public:
+        void add(const double value) {
+            const double next = m_sum + value;
+            m_correction += std::abs(m_sum) >= std::abs(value) ? (m_sum - next) + value : (value - next) + m_sum;
+            m_sum = next;
+        }
+
+        [[nodiscard]] double value() const { return m_sum + m_correction; }
+
+    private:
+        double m_sum{0.0};
+        double m_correction{0.0};
+    };
+}
diff --git a/src/include/serif/utils/misc/concepts/enumeration.hpp b/src/include/serif/utils/misc/concepts/enumeration.hpp
deleted file mode 100644
index ea76794e..00000000
--- a/src/include/serif/utils/misc/concepts/enumeration.hpp
+++ /dev/null
@@ -1,18 +0,0 @@
-#pragma once
-
-#include "serif/utils/misc/concepts/concat.hpp"
-#include "serif/utils/types/type_list.hpp"
-
-namespace serif::utils::misc::concepts {
-    // Might make sense to rename these to FlatMap or some such
-    template <typename TypeList, template <typename> typename Descriptor>
-    struct EnumerateTypes;
-
-    template <template <typename> typename Descriptor, typename... TypeTs>
-    struct EnumerateTypes<types::TypeList<TypeTs...>, Descriptor> {
-        using Type = ConcatT<Descriptor<TypeTs>...>;
-    };
-
-    template <typename TypeList, template <typename> typename Descriptor>
-    using EnumerateTypesT = EnumerateTypes<TypeList, Descriptor>::Type;
-}
\ No newline at end of file
diff --git a/src/include/serif/utils/misc/concepts/exceptions.hpp b/src/include/serif/utils/misc/concepts/exceptions.hpp
index 9ef28101..e2aaddd6 100644
--- a/src/include/serif/utils/misc/concepts/exceptions.hpp
+++ b/src/include/serif/utils/misc/concepts/exceptions.hpp
@@ -1,15 +1,10 @@
 #pragma once
 #include <exception>
 #include <type_traits>
-#include <string>
 
 #include "serif/utils/misc/concepts/numeric.hpp"
 
 namespace serif::utils::misc::concepts {
     template <typename ExceptionCandidate>
     concept IsException = std::is_base_of_v<std::exception, ExceptionCandidate>;
-
-    template <typename ExceptionCandidate, typename ErrorCode>
-    concept IsExceptionWithErrorCode = IsException<ExceptionCandidate> &&
-                                       std::constructible_from<ExceptionCandidate, ErrorCode, std::string>;
 }
\ No newline at end of file
diff --git a/src/include/serif/utils/misc/concepts/numeric.hpp b/src/include/serif/utils/misc/concepts/numeric.hpp
index 2ffa7150..80beaed6 100644
--- a/src/include/serif/utils/misc/concepts/numeric.hpp
+++ b/src/include/serif/utils/misc/concepts/numeric.hpp
@@ -7,9 +7,6 @@ namespace serif::utils::misc::concepts {
     template <typename T>
     concept IsNumeric = std::integral<T> || std::floating_point<T>;
 
-    template <typename T>
-    concept IsOrderable = std::totally_ordered<T>;
-
     template <typename T>
     concept IsComparableToNumeric = std::totally_ordered_with<T, float> ||
         std::totally_ordered_with<T, double> ||
@@ -20,7 +17,4 @@ namespace serif::utils::misc::concepts {
 
     template <typename...Ts>
     concept SetOfOneOrTwo = (sizeof...(Ts) == 1) || (sizeof...(Ts) == 2);
-
-    template <typename EnumCandidate>
-    concept IsEnum = std::is_enum_v<EnumCandidate>;
 }
diff --git a/src/include/serif/utils/misc/traits/type_uniqueness.hpp b/src/include/serif/utils/misc/traits/type_uniqueness.hpp
index c4fd8bf9..ab154b66 100644
--- a/src/include/serif/utils/misc/traits/type_uniqueness.hpp
+++ b/src/include/serif/utils/misc/traits/type_uniqueness.hpp
@@ -1,19 +1,19 @@
 #pragma once
 
+#include <array>
 #include "serif/utils/misc/std_helper/cleaning.hpp"
 
 namespace serif::utils::misc::traits {
     template <typename... Ts>
     constexpr bool all_unique_types_v = true;
 
-
-    // This can be a bit confusing. Whats going on here is that !SameType<First, Rest> && ...
-    // is preforming variadic folding. That is we check if First is the same as all types in
-    // the rest type list. If First is the same as any of those this will eval to true and then be negated to false.
-    // The only way for the first term (!SameType<First, Rest> && ...) to be true is if First is not the same as any of the types in Rest.
-    // Then we recursively call all_unique_types_v<Rest...> to check the rest. This ensures that this is only true if
-    // every single type in the type list is unique.
+    /** @brief Compare each head with the remaining exact types without a pack-sized Boolean fold. */
     template <typename First, typename... Rest>
-    constexpr bool all_unique_types_v<First, Rest...> = (!std_helper::SameType<First, Rest> && ...) && all_unique_types_v<Rest...>;
-
+    constexpr bool all_unique_types_v<First, Rest...> = [] {
+        constexpr std::array<bool, sizeof...(Rest)> duplicates{std_helper::SameType<First, Rest>...};
+        for (const bool duplicate : duplicates) {
+            if (duplicate) { return false; }
+        }
+        return all_unique_types_v<Rest...>;
+    }();
 }