ted – A (prim­i­tive) to­ken list ed­i­tor

Just like sed is a stream ed­i­tor, ted is a to­ken list ed­i­tor. Ac­tu­ally, it is not as pow­er­full as sed, but its main fea­ture is that it re­ally works with to­kens, not only char­ac­ters.
The ted pack­age pro­vides two user macros: \Sub­sti­tute and \ShowTo­kens. The first is maybe the most use­ful: it per­forms sub­sti­tu­tions in to­ken lists (even in­side braces). The sec­ond dis­plays each to­ken of the list (one per line) with its cat­code (in the list, not just the cur­rent one), and can be use­ful for de­bug­ging or for TeX learn­ers.
Ted is de­signed to work well even if strange to­kens (that is, un­usual {char­code, cat­code} pairs or to­kens with a con­fus­ing mean­ing) oc­cur in the list.