I am reading a textbook which uses the LaTeX
\smile symbol (a sort of sideways parenthesis) for concatenation of lists. I have never seen this symbol anywhere before except in the document which lists all LaTeX symbols. It may be that this use of
\smile for concatenation is standard, and has passed me by. I myself either simply use + for concatenation, or if in pseudo code write it out in words.
Anyway, I'm just curious as to this use of the smile symbol.