This is heavy biased to C++, which is a language that already has too many features that people just want to use. This is a very specific case to be placed as a

This is heavy biased to C++, which is a language that already has too many features that people just want to use. This is a very specific case to be placed as a language feature, and could be just a lib. If this becomes a C++ feature, imagine how many data structures we would need to support? Many other languages, specially the FP languages, allow to do that as a library. Even the languages that are only inspired by FP. Example, Ruby: class BinTree include Enumerable def initialize v, l, r @v, @l, @r = v, l, r end def each &block @l.each(&block) unless @l.nil? yield @v @r.each(&block) unless @r.nil? end end Using the Enumerable mixin includes many FP-based methods, such as map, filter and reduce by only defining each, which in this case is DFS. Then we can proceed to define a binary tree: tree = BinTree.new( 1, BinTree.new( 2, BinTree.new(4, nil, nil), BinTree.new(5, nil, nil) ), BinTree.new( 3, BinTree.new(6, nil, nil), BinTree.new(7, nil, nil), ) ) Iterate over all the elements: tree.each{|v| puts v} Iterate over the even elements: tree.filter{|v| v.even?}.each{|v| puts v} Stop iteration when finding a value: tree.each do |v| break if v == 1 puts v end And so on. The same can be done in Python, Kotlin and many others.