diff --git a/2023/xmaslib/integer_range/integer_range.hpp b/2023/xmaslib/integer_range/integer_range.hpp
index 82569c6..ee38fbf 100644
--- a/2023/xmaslib/integer_range/integer_range.hpp
+++ b/2023/xmaslib/integer_range/integer_range.hpp
@@ -22,6 +22,11 @@ struct integer_range {
     assert(begin <= end);
   }
 
+  constexpr integer_range(auto pair) {
+    const auto& [begin, end] = pair;
+    integer_range(begin, end);
+  }
+
   constexpr bool empty() const noexcept {
     return begin == end;
   }
diff --git a/2023/xmaslib/matrix/matrix.hpp b/2023/xmaslib/matrix/matrix.hpp
index 7799349..4d5b861 100644
--- a/2023/xmaslib/matrix/matrix.hpp
+++ b/2023/xmaslib/matrix/matrix.hpp
@@ -77,6 +77,11 @@ struct matrix {
     return row(r);
   }
 
+  auto operator[](auto rc) const {
+    auto const& [r, c] = rc;
+    return row(r)[c];
+  }
+
   std::span<T> data() noexcept {
     return m_data;
   }
diff --git a/2023/xmaslib/matrix/text_matrix.cpp b/2023/xmaslib/matrix/text_matrix.cpp
index b67cd1b..fbd75ce 100644
--- a/2023/xmaslib/matrix/text_matrix.cpp
+++ b/2023/xmaslib/matrix/text_matrix.cpp
@@ -9,11 +9,9 @@
 namespace xmas {
 namespace views {
 
-std::pair<std::size_t, std::size_t> text_matrix::dimensions(
-  std::string_view input) {
+std::pair<std::size_t, std::size_t> text_matrix::dimensions(std::string_view input) {
   const std::size_t ncols =
-    1 +
-    std::size_t(std::find(input.cbegin(), input.cend(), '\n') - input.cbegin());
+    1 + std::size_t(std::find(input.cbegin(), input.cend(), '\n') - input.cbegin());
   const std::size_t nrows = input.size() / ncols;
   xlog::debug("Detected {} rows and {} columns", nrows, ncols);
 
@@ -33,10 +31,16 @@ view<std::string::iterator> text_matrix::row(std::size_t i) {
     text.begin() + static_cast<std::ptrdiff_t>(pos + n_cols)};
 }
 
+std::string_view text_matrix::line(std::size_t i) const {
+  assert(i < n_rows);
+  const std::size_t pos = i * (n_rows + 1);
+  return {text.begin() + static_cast<std::ptrdiff_t>(pos),
+    text.begin() + static_cast<std::ptrdiff_t>(pos + n_cols)};
+}
+
 strided<std::string::iterator> text_matrix::col(std::size_t j) {
   assert(j < n_cols);
-  return {
-    text.begin() + static_cast<std::ptrdiff_t>(j), text.end(), n_cols + 1};
+  return {text.begin() + static_cast<std::ptrdiff_t>(j), text.end(), n_cols + 1};
 }
 
 char text_matrix::at(std::size_t i, std::size_t j) const {
diff --git a/2023/xmaslib/matrix/text_matrix.hpp b/2023/xmaslib/matrix/text_matrix.hpp
index 5438145..eaa584f 100644
--- a/2023/xmaslib/matrix/text_matrix.hpp
+++ b/2023/xmaslib/matrix/text_matrix.hpp
@@ -14,6 +14,8 @@ struct text_matrix {
   text_matrix(std::string& data);
 
   [[nodiscard]] view<std::string::iterator> row(std::size_t i);
+  [[nodiscard]] std::string_view line(std::size_t i) const;
+
   [[nodiscard]] strided<std::string::iterator> col(std::size_t j);
 
   [[nodiscard]] char at(std::size_t i, std::size_t j) const;
@@ -35,6 +37,11 @@ struct text_matrix {
            std::ranges::views::transform([this](std::size_t r) { return row(r); });
   }
 
+  auto lines() const {
+    return std::ranges::views::iota(std::size_t{0}, n_rows) |
+           std::ranges::views::transform([this](std::size_t r) { return line(r); });
+  }
+
   auto cols() {
     return std::ranges::views::iota(std::size_t{0}, n_cols) |
            std::ranges::views::transform([this](std::size_t c) { return col(c); });