On Mon, Feb 8, 2010 at 8:24 PM, David Ward Lambert
<b49p23t...@stny.rr.com>wrote:
> Novice wishes from an accessible dictionary.
>
> 0) Will the accessible dictionary help me understand errors? For
> example, "Why does this raise domain error instead of dividing by three
> the result after evaluating a polynomial?"
>
> r2 =: %&3 @ _1 2&p.
>
I wonder if we might also need a basic work on J grammar.
In this case your error is because the above statement is equivalent to:
r2 =: (%&3 @ _1 2)&p.
And, any statement of the form v...@noun will generate a domain
error, because nouns currently are not in the domain of @
So... hypothetically speaking, if you had thought to look up @
you would have found the reason for your error.
There might also be some justification here for J error messages to
report the name of the primitive which is having the domain
problem.
> 1) This sentence about `agenda' in the dictionary: "The case m...@.v uses
> the result of the verb v to perform the selection." leaves me asking
> "v called with which arguments?", and I worry, "Am I restricted to
> monadic v?". The prior sentence about boxing and parenthesizing is so
> nebulous that it doesn't concern me. Examples \textit{must} follow.
>
The arguments to m...@.v are also the arguments to v
This kind of information does belong in a beginner's dictionary.
And, no, not only are you not restricted to monadic v, but if you
assume v will be used monadically and you use m...@v dyadically,
things will not work the way you would expect.
> And I also comment that you ought to consider downplaying valence. The
> functions have natural names and valences.
>
I do not understand your point of view here. Your previous question was
about valence and I imagine other beginners might have other issues
with valence.
However, I do think we need to present information about valence clearly.
--
Raul
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
