Call/cc is actually used by Sinatra for its error handling. There's not a good way to get its syntax without doing it that way. (Is the syntax worth using call

Call/cc is actually used by Sinatra for its error handling. There's not a good way to get its syntax without doing it that way. (Is the syntax worth using call/cc? Eh, good question. But Sinatra's killer feature is, literally, its syntax, so I don't think I get to tell them "don't do it that way." Rails has an ugly workaround for not using call/cc that bites many, many app programmers who forget to return after calling render().)