A very good reference card is on pages 200-201 of
A. D. Falkoff, et al., "A formal description of SYSTEM/360"
IBM System Journal, Vol. 3, No. 3, 1964.
Note how for such space-constrained text they creatively
use typography:
x, y are real agruments, z is real result
bold *x* is vector, upper case X is matrix
k, n, m are integers
u, v are boolean
etc.
Another important feature, not present in J Dictionary
is grouping by functional sections: Logical,
Numerical, Selection, etc.
--- Micke Hovmöller <[EMAIL PROTECTED]> wrote:
> On 3/28/06, Henry Rich <[EMAIL PROTECTED]> wrote:
> > I am working on a one-sheet reference card for J. It looks like it will fit
> > on front & back of an 8.5x11 sheet if I use an 8-point font. I have a first
> > pass at what I want to include, attached to this email as a text file. I
> > would like comments from interested users before I go through the pain of
> > cramming it onto a page.
>
> I found this to be very promising and something I would definitely
> print, laminate and use regularly.
>
> Will the final result be a neatly formatted .pdf file? I think that is
> almost mandatory in order to optimize readability, even though editing
> .pdfs are of course difficult.
>
> What I would find most useful is a sort of "vocabulary with examples".
> Thus, I'd structure it in one ore more tables as follows:
> <verb or concept> ; <explanation> ; <example>
> Such as:
> + ; Plus ; 2 + 8 -> 10
> <: ; Decrement ; <: 5 7 -> 4 6
>
> The ";" is a placeholder for cells in the table, so that the columns
> line up nicely. The "->" is there to distinguish between the "program"
> and the result. Please use whatever symbol is "standard" for J.
> (Usually, of course, the result goes on a new line, but because of
> space constraints, that is not appropriate here.)
>
> Sometimes you use "y" in the examples and sometimes numbers. I prefer
> numbers, but in either case consistency would be better, I think.
>
> The examples in your file are much simpler than the ones in the
> vocabulary. I think that is very good. The vocabulary often crams too
> many concepts together in one concise example which I find difficult
> to interpret.
>
> Or rather, if there was such a reference card, I'd use it 90% of the
> time. For the final 10%, the examples in the vocabulary are fine,
> because then I wanted to dive deeper into a subject.
>
> > The intended user has a reading knowledge of J but may need some reminding
> > about what the primitives do. My goal is to include one example of all the
> > important idioms of J so that the interested user can look it up in more
> > detail
> > if he finds it promising.
>
> This is very good. I think that it is then important to use the name
> of the verbs as the next step is usually to look up the verbs in the
> vocabulary, when needed.
>
> In some cases where idioms are presented ("<\"), the explanation
> should be set in a different way from a "regular verb" to indicate
> immediately that it is a derivative of some form.
>
> > I don't really expect anyone to review the attached notes in detail, but
> > if y'all would think a minute about what features you have found yourself
> > forgetting, or some feature you didn't find out about for years but now
> > love,
> > let me know if you don't find it listed. I say nothing about useful verbs
> > from the J scripts and I welcome suggestions about what to mention.
>
> As others have mentioned, I would like a graphical representation of
> trains, hooks, forks etc. This is too complicated to describe, but the
> pictures are enough to jog my memory about what to use.
>
> A few of the examples are just too complex for me to parse. An example is:
> ([stepsize,:]shape) u;._3 y operates on regions of y with the given
> shape, starting at all possible multiples of items of stepsize.
> Negative items in shape run that index backwards
>
> Without an example it's just too difficult for me to figure out if
> this is what I want. I understand that since any reasonable example
> would have a multidimensional answer, presenting it may too space
> consuming. Then just skip it, IMHO.
>
> /Micke
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
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