Programming languages should have a tree traversal primitive

There should be a control flow construct in programming languages that can handle tree-like traversal in a nice way, similar to how for/foreach loops can handle linear traversal. It's a bit of a missing gap in the current set of control flow constructs most languages these days have settled on. Its a thing I end up having to do *all the time* and it seems like there should be some shortcuts for it

[yosuke_furukawa]

あー木構造を走査するための新しい構文があってもいいんじゃね？っていう提案か。木構造を表現するデータ型がデフォルトであってもいいんじゃね？っていう議論にもなりそうな。