One of the things that's nice about Common Lisp style conditions is that they do not automatically force a stack unroll. You can, and people do, signal conditi

One of the things that's nice about Common Lisp style conditions is that they do not automatically force a stack unroll. You can, and people do, signal conditions like "I don't know what to do with this" that can be handled inline (say, with the coding table, replacing it with "?" although I personally loathe that "fix") and then the parser goes along its merry way. The same library can be used to say "WTF? this is in no way the data file I wrote out. Bail!".