The domain of !. is limited only by your imagination, guided by a heavy dose of good taste, and the skill and energy of your humble implementer.
----- Original Message ----- From: Henry Rich <[email protected]> Date: Monday, September 6, 2010 6:34 Subject: Re: [Jprogramming] Mask from list of indices with multiplicity To: Programming forum <[email protected]> > !. doesn't apply to to /., but to the verb f/., whatever f may be. > > Yes, it affects only the operation of the /. part of f/. . > > It is not unthinkable for !. to apply to named verbs. I > have often > wished that > > v!.value > > would define a local name, say f, before v starts execution. > > Henry Rich > > On 9/6/2010 7:16 AM, Don Guinn wrote: > > Is it really applying to a bigger-than-primitive, or is > applying to the /. ? > > > > f=.< > > f/.!.0 > > +------+--+-+ > > |+-+--+|!.|0| > > ||f|/.|| | | > > |+-+--+| | | > > +------+--+-+ > > <!.0 > > +-+--+-+ > > |<|!.|0| > > +-+--+-+ > > f!.0 > > |domain error > > | f!.0 > > > > It certainly can't apply to the f because !. applies only to > primitives.> Besides, the< is being used as monadic. It > is /. that does the comparisons. > > > > Never thought about it before, but this is a case where !. > applies to a > > non-verb. Shouldn't /. be added to the list of primitives to > which !. > > applies in the Dictionary? > > > > On Sun, Sep 5, 2010 at 11:03 PM, Henry > Rich<[email protected]> wrote: > > > >> You just need to get rid of the ~ : > >> > >> 1 [`]`(0 $~>:@(>./)@])} ia > >> > >> This is the implementation I would use. I don't see the > need for > >> special code, since the old code seems fast enough. > >> > >> > >> > >> On your earlier point, !. can be used on bigger-than-primitives: > >> > >> f/.!.0 > >> > >> is one I use. It makes sure that intolerant comparison > is used on the > >> grouping performed by /. . > >> > >> Henry Rich ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
