Both JfC and LJ mention a 'solo colon' separating the monadic from the dyadic cases of an explicit verb. Unaware of this, I got caught out recently by adding a comment after the colon. J doesn't like it!
foo=: 3 : 0 -y : x-y ) foo 3 _3 5 foo 3 2 0K! But ... foo=: 3 : 0 -y : NB. No comments allowed on this line! x-y ) foo 3 |value error: x | x-y 5 foo 3 |domain error: foo | 5 foo 3 It appears that the colon should be oh so solo! Regards Graham ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
