There is something like transform-one!? (transform-one! (walker :a) f m) with: Return nil if dosen't apply f in any element Throws or don't apply f if find more then one "match" Return transformed m case find only one "match"

@souenzzo no, nothing like that

easy to implement yourself by wrapping the transform fn

I implemented with select-one before transform. For now, that's enough. 😉