Ask, and you shall be covered in gifts :-) But I have a follow-up question. The function that actually should be applied is rather expensive (it is the distance function of the labyrinth of AoC 24), so it should only be executed on the selected values. This seems not to be the case in
0 0 1 0 0 1 (* >:) i.6 where multiplication with zero happens after >: is computed (or so I read it). Am I right here, is evaluation always strict? Or is there a situation where evaluation of an argument is skipped because the end result does not depend on it? David Louis de Forcrand <[email protected]> writes: > Or > >:@#`(I.@[)`]} > > Louis > >> On 02 Jan 2017, at 02:16, 'Pascal Jasmin' via Programming >> <[email protected]> wrote: >> >> and, >> >> 0 0 1 0 0 1 >:@]^:["0 i.6 NB. passes original unchanged >> >> or as requested, >> >> 0 0 1 0 0 1 [`(>:@])@.["0 i.6 >> >> >> >> ----- Original Message ----- >> From: 'Pascal Jasmin' via Programming <[email protected]> >> To: "[email protected]" <[email protected]> >> Sent: Sunday, January 1, 2017 8:10 PM >> Subject: Re: [Jprogramming] dyadic valence of v in u&.v ? >> >> not what was asked but there is also >> >> 0 0 1 0 0 1 (* >:) i.6 >> >> >> >> >> ----- Original Message ----- >> From: Henry Rich <[email protected]> >> To: [email protected] >> Sent: Sunday, January 1, 2017 4:51 PM >> Subject: Re: [Jprogramming] dyadic valence of v in u&.v ? >> >> You can't save it using &. . But nothing stops you from writing your >> own conjunction. >> >> semidual =: 2 : 0 >> : >> u&.(x&v) y >> ) >> >> Henry Rich >> >>> On 1/1/2017 3:40 PM, David Koppenhoefer wrote: >>> Reading the wonderful NuVoc I found the gem that dyadic # has an inverse >>> - it can therefore be used in &. like >>> >>>> : &. (0 0 1 0 0 1&#) i.6 >>> 0 0 3 0 0 6 >>> >>> , executing a function only on selected items of an array while keeping >>> the shape. >>> >>> The bit array is a noun, but I want to compute it on the fly (from the >>> right argument). If the v in u&.v had dyadic valence, something like >>> >>> 0 0 1 0 0 1 >:@] &. # i.6 >>> >>> would be possible and the left argument could be replaced by a >>> computation. Here I'm stuck. From what I understood so far this seems to >>> be impossible - the v in the &-conjunctions is always monadic. Is >>> there a way to save the idea? >>> >>> >>> P.S.: needed in AoC day 24... >>> ---------------------------------------------------------------------- >>> 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
