'' is the shortest and simplest empty list, so it's fairly popular. I hope this helps,
-- Raul On Wed, Jun 7, 2017 at 11:58 AM, Michael Rice <[email protected]> wrote: > f EMPTY > > 2+3 > 5 > > where f is (1&,), returns a blank line and then is ready for more input. > > This seems to work ok: > > my_empty =: }. 1 > > my_empty > > > f my_empty > > 1 > > > Many different answers. Is there some consensus about how to pass an empty > list to a function? > > > > On Wed, Jun 7, 2017 at 11:39 AM, Michael Rice <[email protected]> wrote: > >> Oops! Guess I creamed empty. Will close and regen Jqt before proceeding. >> >> Done! >> >> f =: (1&,) >> f 2 >> 1 2 >> f empty >> f empty >> >> Shouldn't it have returned >> >> 1 >> >> ? >> >> On Wed, Jun 7, 2017 at 11:22 AM, robert therriault <[email protected]> >> wrote: >> >>> 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
