4 points by fallintothis 5450 days ago | link First-class continuations & call/cc are notoriously difficult to explain (and indeed, can be hard to understand in code that uses them). Your best bet is to Google around for info, seeing if you can make sense of the (vast) material available. http://en.wikipedia.org/wiki/Call-with-current-continuation and http://community.schemewiki.org/?call-with-current-continuat... might be good starts.As for point 5, Arc uses certain characters as syntax abbreviations iff the special characters occur in what would otherwise be normal symbols (to the Scheme reader). So far, there's`````` .a ; is the same as (get a) a.b ; is the same as (a b) !a ; is the same as (get 'a) a!b ; is the same as (a 'b) f&g ; is the same as (andf f g) f:g ; is the same as (compose f g) ~f ; is the same as (complement f) `````` where`````` ((get a) b) ; is the same as (b a) by Arc's indexing ; e.g., ("abc" 0) is #\a ((andf f g) x) ; is the same as (and (f x) (g x)) ((compose f g) x) ; is the same as (f (g x)) ((complement f) x) ; is the same as (no (f x)) `````` See arc.arc for the actual definitions of these operators.There are precedence and associativity rules, such as`````` a!b.c ; is the same as ((a 'b) c) because ! and . are ; left-associative f:g:h ; is the same as (compose f g h) ~f:g ; is the same as (compose (complement f) g) `````` To explore these more, you can use the ssexpand function in Arc:`````` arc> (ssexpand 'a:b.c!d) (compose a b.c!d) arc> (ssexpand 'b.c!d) ((b c) (quote d))``````-----
 2 points by conanite 5450 days ago | link call/cc, (or ccc in arc) isn't actually used very much in the official distribution, except to provide escape routines, à la`````` (catch (each x xs (if (foo x) (throw x)))) `````` so you don't need to go all the way to the end of a loop.The last time I looked, ccc isn't used to capture and re-use first-class continuation objects except for this escape-clause purpose.Here's a fine article on the subject - http://www.intertwingly.net/blog/2005/04/13/Continuations-fo...And here's a long-winded, verbose, java-oriented article I wrote last year in an attempt to explain ccc in java terms - http://www.fnargs.com/2008/05/continuations-arc-vs-java.html-----