So monad u/ returns {.y if 1=#y regardless of u?
One might think that it would be different,
with rank 1 arguments, for atom valued +/ and
vector valued ,/ when 1~:#y.
ins1=: 1 : 0
".'v=.',u b.1
z=. v y
for_i. |.y do.
z=. i u z end.
z
)
However, it most likely modeled as below
ins2=: 1 : 0
if. 0=#y do.
".'v=.',u b.1
v y end.
z=. {:y
for_i. }.|.y do.
z=. i u z end.
z
)
That is when 1=#y, u is not even accessed in any way
even for identity.
$bogus/ 'a'
$bogus/ ,'a'
$bogus/ ,'ab'
|value error: bogus
| $ bogus/,'ab'
bogus ins2 1
1
bogus ins1 1
|value error: bogus
| ".'v=.', u b.1
--- Roger Hui <[EMAIL PROTECTED]> wrote:
> The monad ,/ should also work for this problem.
> That it does not is a bug in the interpreter and
> will be fixed for J6.02.
>
> $ ,/ 1$'a' NB. wrong
> 1
> append=: ,
> $ append/ 1$'a' NB. correct
>
> $ append/ 'a' NB. correct
>
> append/ 'abc' NB. correct
> abc
>
>
>
> ----- Original Message -----
> From: Roger Hui <[EMAIL PROTECTED]>
> Date: Saturday, April 7, 2007 10:25 am
> Subject: Re: [Jprogramming] Singleton Reduction
>
> > f=: {.^:(1=#)
> > f 'abc'
> > abc
> > $ f 'a'
> >
> > $ f ,'a'
> >
> > f^:proprosition y is equivalent to
> > if. proposition y do. f y else. y end.
> >
> >
> >
> > ----- Original Message -----
> > From: "Leigh J. Halliwell" <[EMAIL PROTECTED]>
> > Date: Saturday, April 7, 2007 10:14 am
> > Subject: [Jprogramming] Singleton Reduction
> >
> > > Dear J Forum:
> > >
> > > Let X1 =. 'A' and X2 =. 1$'A'. Now X1 and X2 look equal, but
> > > because of
> > > different ranks X1 does not equal X2. I would like to reduce a
> > > singleton to
> > > an atom. If #X is 1, {.X does this. But I don't want to take
> > the
> > > firstitem, if the string has more than one item. Can someone
> > tell
> > > me a simple or
> > > efficient tacit expression that reduces one-rank, one-item
> > arrays
> > > to atoms,
> > > and leaves other one-rank arrays unchanged? Can it be done
> > > without gerunds?
> > > Thanks.
> > >
> > > Sincerely,
> > >
> > > Leigh
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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