Post #2557970
2026-05-13 16:00 UTC
It turns out that the ugly convention of completing a command input with two Return characters (as found in AutoCAD, for example) is a TECO-ism.
In TECO, you're building a (possibly empty) command string (approximately, a list of commands).
In Autocad this convention usually has the flavour of terminating a list of items with an empty item, so it's a kind of in-band signalling.
Replies (2)
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@theohonohan@graphics.social 2026-05-13 16:16
The distinction between an empty list and a list containing only an empty string is a bit like this advanced math scenario https://mathoverflow.net/a/46073 I suppose it only works in the setting where you're implicitly concatenating the strings, "" being the identity of that operation. I wish I knew more about this, but the obvious point is that a list of empty strings (how long?) contains more information than one empty string.
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@drawkcab@hachyderm.io 2026-05-13 22:32
@theohonohan@graphics.social I initially thought that might be a sensible decision for a world where CR and LF were still distinct. But then they ruined it all with bonkers stuff about DELIM and accent grave