File access error can happen when permission is denied by the host operating system.
For example: $ date >/tmp/example; chmod 0 /tmp/example; ijconsole 1!:1<'/tmp/example' |file access error | 1!:1<'/tmp/example' I think allocation error is similar - I expect that it would happen when J asks for memory and none is available (it's analogous to ws full - but it's not happening inside J's accounting system). Thanks, -- Raul On Tue, May 20, 2014 at 6:08 PM, Roger Hui <[email protected]>wrote: > s=: 1 $. 100;0;2 > t=: 1 $. 200;0;3 > s,"0/t > |non-unique sparse elements > | s ,"0/t > > For that matter, I'd expected that s,t would signal the same error, but it > doesn't. I guess if I looked at the source I can figure out why that is. > > s,t > |nonce error > | s ,t > > In contrast: > > s ,"0/ s > $ s ,"0/ s > 100 100 2 > 3 $. s ,"0/ s NB. the sparse element > 2 > > I expect "read only data" to be signaled if you try to amend data which is > mapped on a read-only file (e.g. if the mapped file is on a CDROM). > > "stop" would be signaled when execution reaches a line in an explicit defn > which has stop set. > > "break" would be signaled if (on Windows) you hit the yellow J icon while > the J session is executing. e.g. execute 6!:3]100 and then hit the yellow > icon 2 or 3 times. > > "input interrupt" would be signaled if you asked for "terminal input", > 1!:1]1, hit the yellow icon, and then enter. It dates from a time when it > was possible to enter o backspace u backspace t (remember that?) in > response to 1!:1]1. > > "system error" is not supposed to happen. > > Not sure about "file access error". > > > > > > On Tue, May 20, 2014 at 2:32 PM, Ian Clark <[email protected]> wrote: > > > For NuVoc purposes I'm documenting J's error messages... > > > > Have you ever seen any of the following error messages in your J session > > (j602 onwards)? > > > > allocation error > > break > > file access error > > input interrupt > > non-unique sparse elements > > read-only data > > stop > > system error > > > > If so, can you furnish a simple sample of "normal" J code that causes the > > said error? > > > > I specify "normal" because I don't want samples which rely on > constructing > > a pathological noun as a core image in hex and shoe-horning it into J by > > use of 3!:2, or use of the "darker" Foreigns, especially undocumented > ones. > > I want something which could conceivable arise by bona-fide J usage by an > > innocent newbie, ill-conceived though it might seem to someone more > > experienced. > > > > Having said that, it probably takes deep knowledge of the J source to > know > > what might trigger some of these errors. > > > > It would also be nice to know which of the above error messages can't > > possibly arise in normal usage. (But consider it "cheating" to use 13!:8 > to > > signal any given message: assume I know how to do that.) > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
