As far as I understand, the rationale comes from the way J parses its
sentences, as explained in section E of the dictionary
(http://www.jsoftware.com/help/dictionary/dicte.htm).
When you assign a name to a verb, and the parser then runs into that name, it
has to be considered as a valid verb, not as a sequence of symbols.
However, when you're assigning the tacit verb, you can instead use the '13 :'
definition to generate your tacit verb:
] f =. 13 : '+/ ! >: 2 * i. y'
[: +/ [: ! [: >: 2 * i.
f 5
368047
If I am programming quickly i will often use '13 :' to define verbs before
going back and optimizing them.
It is important however to learn the use of cap ( [: ) in a verb train, so as
not to rely on the interpreter to do the heavy lifting of writing the program,
rather than running it.
[2018-07-07 17:06]
>
> part text/plain 1873
> Hmmm.. parentheses are automatically added when I assign a name to a verb!
> What is the rationale for always adding parentheses when assinging a name
> to a verb? It seems to be unnecessarily complicating a simple process.
>
> In any case, what method can I use to remove those parentheses, or at least
> nullify their effect, when assiging a name?
>
> Skip
>
>
>
> On Sat, Jul 7, 2018 at 4:12 PM Henry Rich <[email protected]> wrote:
>
> > Assigning to a name adds an implied set of parentheses. Thus if you write
> >
> > f =. +/!>:2*i.
> >
> > When you execute
> >
> > f 5
> >
> > you will get the same result as if you had executed
> >
> > (+/!>:2*i.) 5
> >
> > Try it and see.
> >
> > Henry Rich
> >
> >
> > On 7/7/2018 5:07 PM, Skip Cave wrote:
> > > I have a tacit verb that finds the sum of the factorials of the odd
> > > integers from 1 to 2n - 1:
> > >
> > > +/!>:2*i.1
> > >
> > > 1
> > >
> > > +/!>:2*i.2
> > >
> > > 7
> > >
> > > +/!>:2*i.3
> > >
> > > 127
> > >
> > > +/!>:2*i.4
> > >
> > > 5167
> > >
> > > I want to assign that tacit verb a name f:
> > >
> > > f=. +/!>:2*i
> > >
> > > f 1
> > >
> > > 2
> > >
> > > f 2
> > >
> > > 3 3
> > >
> > > f 3
> > >
> > > 4 4 4
> > >
> > > f 4
> > >
> > > 5 5 5 5
> > >
> > >
> > > My tacit verb doesn't work the same when I assign it a name. How do I
> > > modify the verb to allow me to name it? Why do I have to change my verb,
> > > just because I assign it a name?
> > >
> > > Skip
> > >
> > >
> > > Skip Cave
> > > Cave Consulting LLC
> > > ----------------------------------------------------------------------
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> >
> >
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