maybe worth noting, '' -: i.0 1
________________________________ From: robert therriault <[email protected]> To: [email protected] Sent: Wednesday, June 7, 2017 11:22 AM Subject: Re: [Jprogramming] Empty lists? One thing to remember is that empty is already defined as a verb empty (i.0 0)"_ So if you overwrite this you may break some code if you have previously relied on the existing verb definition. I think along the lines that Pascal mentioned that null could be similarly defined as null NB. check that it is not already used |value error: null null=:(i.0)"_ NULL NB. check that it is not already used - uppercase for global nouns is a convention I like and is often seen in J code |value error: NULL NULL=:'' NB. I use this as the null string (same as what John suggested) NULL-:null 2 NB. any argument produces NULL from null 1 Hope this helps, Cheers, bob > On Jun 7, 2017, at 8:09 AM, 'Jon Hough' via Programming > <[email protected]> wrote: > > > I may be wrong in doing this, but I usually write > empty=: '' > to signify an empty list, array, matrix etc. > > > On Jun 7, 2017, 23:59, at 23:59, Michael Rice <[email protected]> wrote: >> Is there a special "noun" for an empty list? >> >> Creating one seems enigmatic. >> >> empty =: 1 2 >> empty >> 1 2 >> empty =: }. empty >> empty >> 2 >> empty =: }. empty >> empty >> >> empty1 =: >> |syntax error >> | empty1=: >> ---------------------------------------------------------------------- >> 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
