ranges: add izip helper

cruft/util/CMakeLists.txt

@@ -546,6 +546,7 @@ list (
     range.hpp
     ranges/chunk.hpp
     ranges/enumerate.hpp
+    ranges/izip.hpp
     rational.cpp
     rational.hpp
     region.cpp

cruft/util/ranges/izip.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <ranges>
+
+
+namespace cruft::ranges {
+    /// A convenience function that combines enumerate and zip, such that a preceding index element is returned in
+    // the result tuple.
+    template <::std::ranges::viewable_range... Rs>
+    constexpr ::std::ranges::view auto
+    izip (Rs &&...rs)
+    {
+        return ::std::views::zip (
+            ::std::views::iota (0),
+            ::std::forward<Rs> (rs)...
+        );
+    }
+}