It's not the [: which is preventing 13 : from giving you a tacit result. It's the y in the right conjunction argument to ^: which is preventing 13 : from giving you a tacit result.
That said, 13 : doesn't really do anything useful here. As for the Y combinator... it's something that should normally never be used (with an exception for people who write or document utility code that takes code as arguments - if you are doing that kind of work, it's kind of important to draw pictures of examples of Y combinator expression intermediate results or in some other way work with it in concrete examples, until you understand how it works). Thanks, -- Raul -- Raul On Tue, Nov 13, 2018 at 12:46 PM Linda Alvord <[email protected]> wrote: > > Mike, that was great!! > > I managed to deal with odds and evens. > > However, because of [: which I can't seem to remove, it won't turn tacit. > > It is almost "high school ready" > > flla=: 13 :'1{"1([:+/\|.)^:(<:i.y)1 1' > flla 10 > 1 1 2 3 5 8 13 21 34 55 > flla 11 > 1 1 2 3 5 8 13 21 34 55 89 > flla > ┌─┬─┬─────────────────────────┐ > │3│:│1{"1([:+/\|.)^:(<:i.y)1 1│ > └─┴─┴─────────────────────────┘ > > Linda > > -----Original Message----- > From: Programming <[email protected]> On Behalf Of > 'Mike Day' via Programming > Sent: Monday, November 12, 2018 1:59 PM > To: [email protected] > Subject: Re: [Jprogramming] Revisisting the Y combinator > > NB. I've omitted Jose's rather lengthy original posting to save space. > > Re Linda's quoted Fibonacci verb, > > 13 :',(([:+/\|.)^:2)^:(<`(1,1:))y' > > I couldn't understand it until I checked the vocabulary entry for ^: > > a) u ^: (<n) does the same as u ^: (i.n) > > b) u ^: (v1`v2) y does u^:(v1 y) (v2 y) > > The engine of this fibonacci sequence generator is > > ([:+/\|.) > > as in > > ([:+/\|.) 1 1 NB. f2 f3 given f1 f2 = 1 1 > 1 2 > > The rest is controlling the repetition of the engine's application. > > So, developing the sequence, > > ([:+/\|.)^:(0 1 2 3 4) 1 1 NB. generate pairs f2 f3, f3 f4, ... ,f5 f6 > 1 1 > 1 2 > 2 3 > 3 5 > 5 8 > > ([:+/\|.)^:2^:(0 1 2) 1 1 NB. only generate "even" pairs > 1 1 > 2 3 > 5 8 > > ([:+/\|.)^:2^:(<3) 1 1 NB. using ^: property (a), as above, > 1 1 > 2 3 > 5 8 > > ([:+/\|.)^:2^:(<`(1,1:)) 3 NB. gerund form of power, see (b) above > 1 1 > 2 3 > 5 8 > > ,([:+/\|.)^:2^:(<`(1,1:)) 3 NB. ravel result > 1 1 2 3 5 8 > > I can't get my head round the Y combinator, but this isn't an example! > > Linda wondered why it stopped at 34 or 89 but not 55. > By its construction , this Fibonacci only does even numbers, yielding > elements 1 to 2*y > > We could start from f0 f1, ie 0 1: > > ,([:+/\|.)^:2^:(<`(0,1:)) 3 NB. odd-number version > 0 1 1 2 3 5 > > Cheers, > > Mike > > > On 12/11/2018 08:20, Linda Alvord wrote: > > Sorry about the post in the wrong thread. > > > > There should be some "Y combinator" at work in here. > > > > f=: 13 :',([:+/\|.)^:2^:(<`(0,1:))y' > > > > > > f 5 > > 0 1 1 2 3 5 8 13 21 34 > > f 6 > > 0 1 1 2 3 5 8 13 21 34 55 89 > > > > I can't seem to stop at 55. Any ideas? > > > > Linda > > > > -----Original Message----- > > From: Programming <[email protected]> On Behalf > > Of Linda Alvord > > Sent: Friday, November 9, 2018 12:56 AM > > To: [email protected] > > Subject: Re: [Jprogramming] Revisisting the Y combinator > > > > Jose, I'm not sure I'll be able to follow your ideas. > > > > !i.11x > > 1 1 2 6 24 120 720 5040 40320 362880 3628800 > > > > > > However, Fibohacci would be a nice primitive. > > > > Linda > > > > -----Original Message----- > > From: Programming <[email protected]> On Behalf > > Of 'Pascal Jasmin' via Programming > > Sent: Thursday, November 8, 2018 10:41 PM > > To: [email protected] > > Subject: Re: [Jprogramming] Revisisting the Y combinator > > > > > > > > > > Interesting, thank you Jose. > > > > I'll note that if the argument to Y is not an ar of an adverb then J (806 > > and 807) will crash when the result verb is called. > > > > > > ________________________________ > > From: Jose Mario Quintana <[email protected]> > > > > > --- > This email has been checked for viruses by Avast antivirus software. > https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.avast.com%2Fantivirus&data=02%7C01%7C%7C70903383dc2f4151efd808d648d0decc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636776459254645130&sdata=mP7rC7yN%2BuJS4qiMVFghLinRoT3ekbmvO7oRI4xHtqc%3D&reserved=0 > > ---------------------------------------------------------------------- > For information about J forums see > https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jsoftware.com%2Fforums.htm&data=02%7C01%7C%7C70903383dc2f4151efd808d648d0decc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636776459254645130&sdata=6k9%2FprHwUzkgNvyoCY0efJMeeQb4x3EJogOrQXXXCJk%3D&reserved=0 > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
