diff --git a/solanaceae/file/file2.hpp b/solanaceae/file/file2.hpp
index 9024b18..1ede998 100644
--- a/solanaceae/file/file2.hpp
+++ b/solanaceae/file/file2.hpp
@@ -20,6 +20,6 @@ struct File2I {
 
 	// pos -1 means stream, append to last written, or read position (independent, like FILE*s)
 	virtual bool write(const ByteSpan data, int64_t pos = -1) = 0;
-	virtual std::variant<ByteSpan, std::vector<uint8_t>> read(uint64_t size, int64_t pos = -1) = 0;
+	[[nodiscard]] virtual std::variant<ByteSpan, std::vector<uint8_t>> read(uint64_t size, int64_t pos = -1) = 0;
 };
 
diff --git a/solanaceae/util/span.hpp b/solanaceae/util/span.hpp
index 06a26da..faacd8c 100644
--- a/solanaceae/util/span.hpp
+++ b/solanaceae/util/span.hpp
@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <stdexcept>
 #include <vector>
+#include <array>
 
 // non owning view
 template<typename T>
@@ -10,9 +11,21 @@ struct Span final {
 	const T* ptr {nullptr};
 	uint64_t size {0};
 
+	constexpr Span(const Span&) = default;
+	constexpr Span(Span&&) = default;
 	constexpr Span(void) {}
 	constexpr Span(const T* ptr_, uint64_t size_) : ptr(ptr_), size(size_) {}
+	constexpr Span(T* ptr_, uint64_t size_) : ptr(ptr_), size(size_) {}
 	constexpr explicit Span(const std::vector<T>& vec) : ptr(vec.data()), size(vec.size()) {}
+	constexpr explicit Span(std::vector<T>& vec) : ptr(vec.data()), size(vec.size()) {}
+	template<size_t N> constexpr explicit Span(const std::array<T, N>& arr) : ptr(arr.data()), size(arr.size()) {}
+	template<size_t N> constexpr explicit Span(std::array<T, N>& arr) : ptr(arr.data()), size(arr.size()) {}
+
+	Span& operator=(const Span& other) {
+		ptr = other.ptr;
+		size = other.size;
+		return *this;
+	}
 
 	explicit operator std::vector<T>() const {
 		return std::vector<T>{ptr, ptr+size};
@@ -26,6 +39,16 @@ struct Span final {
 		return ptr[i];
 	}
 
+#if 0
+	constexpr T& operator[](uint64_t i) {
+		if (i > size) {
+			throw std::out_of_range("accessed span out of range");
+		}
+
+		return ptr[i];
+	}
+#endif
+
 	constexpr const T* cbegin(void) const { return ptr; }
 	constexpr const T* cend(void) const { return ptr+size; }
 	constexpr const T* begin(void) const { return ptr; }
@@ -36,4 +59,5 @@ struct Span final {
 
 // useful alias
 using ByteSpan = Span<uint8_t>;
+using ConstByteSpan = Span<const uint8_t>; // TODO: make use of?