On 15/11/2005, at 7pm, Benjamin BAYART wrote: > Le Tue, Nov 15, 2005 at 10:51:30AM +1030, Will Robertson: >> >> So we get ... (other "1") (cseq "\previouslet") (cseq "\test") >> and end up with the equivalent of \let\test=1 . >> >> Ohhh, but I think I get it now. This is no more useful than actually >> looking at nodes, since anything that survives to be \previouslet >> will be turned into a node anyway. > > Yes. It's more clearly seen with: > > \hbox{a}\previouslet\test > > What is \test? The right brace? The box? The box is not a token any > more. So we have to keep on that: > - look ahead for tokens > - look backward for nodes. Yes, it is [or would be] the right brace. That is the previous token, before what came prior to \previouslet triggered the building of a node. I'm not saying this would be a particularly useful feature at this point :) I've been convinced that \previouslet isn't useful, but not that it isn't possible; but who wants possible if it's useless, right? Thanks all for the exposition, Will