Thank you Dan and David, --- (`'') is an anonymous tacit adverb that will produce the atomic rep of its verb argument that seems pretty cool, but I haven't been able to grasp a use for it yet.
----- Original Message ----- From: Dan Bron <[email protected]> To: "[email protected]" <[email protected]> Cc: "[email protected]" <[email protected]> Sent: Saturday, November 2, 2013 4:57:00 PM Subject: Re: [Jprogramming] making a 'first' adverb tacit When the indices to @. are in order and unboxed, the "agenda trick" is overkill. Straightforward, non-tricky adverbs can be defined tacitly with (`:6), as in first =: (`i.) (`1:) (`:6) retitem =: ({~`) (]`) (`:6) If you care for a longer exposition, see [1]. -Dan [1] "A phrase for amendment" & a primer on how to write adverbs tacitly: http://www.jsoftware.com/pipermail/programming/2010-November/021172.html Please excuse typos; composed on a handheld device. > On Nov 2, 2013, at 4:54 PM, Pascal Jasmin <[email protected]> wrote: > > > > I assume only the agenda trick can do it tacitly: > > firstT =: (`(i.`1:))(@.(<0 1 2)) > > There is an upto 10% performance improvement (sometimes in J6. Not J7) in > the tacit version but both are very fast. > > ----- Original Message ----- > From: Pascal Jasmin <[email protected]> > To: "[email protected]" <[email protected]> > Cc: > Sent: Saturday, November 2, 2013 2:06:56 PM > Subject: [Jprogramming] making a 'first' adverb tacit > > I'm pleased that this is as elegant as it is already, but can the 2 adverbs > be defined tacitly? > > first =: 1 : 'u i. 1:' > retitem =: 1 : '] {~ u' > > (4<])first i.7 > 5 > 4< first i.7 > 5 > > Its nice that the adverb doesn't require a duplicate dyadic definition. > > 4< first >:i.7 > 4 > 4< first retitem >:i.7 > 5 > > ---------------------------------------------------------------------- > 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
