I have found it easier to remember hook by considering it as special case of a fork, with an appropriate identity function: i.e.
(f g) y <=> (] f g) y <=> (] y) f (g y) Rgds Ken -----Original Message----- From: programming-boun...@jsoftware.com [mailto:programming-boun...@jsoftware.com] On Behalf Of Marc Simpson Sent: 21 January 2012 10:57 To: Programming forum Subject: Re: [Jprogramming] Morning exercise On Sat, Jan 21, 2012 at 9:39 AM, Linda Alvord <lindaalv...@verizon.net> wrote: > > Are there rules for specific verbs to behave differently when they are next > to each other? I'm not sure that I understand the question-you're demonstrating hooks in the above; given your definitions, p=: -:|. n=: *% the left hand verb in the train (hook) will be called in a dyadic context. In other words, (f g) y <=> y f (g y) as such, you're not using halve in 'p' or signum in 'n'; rather, match and times. Perhaps this clarifies things, p 23 1 (-: |.) 23 1 23 (-: |.) 23 1 23 -: |. 23 1 23 -: (|. 23) 1 Similarly for n, n 23 1 (* %) 23 1 23 (* %) 23 1 23 * (% 23) 1 Best, M ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
