collected questions on J 
Author Message
 collected questions on J

About a month ago I started a discussion "Collected
Questions on J" in which I suggested collecting
questions (topics) on those areas of J in which
people (in particular new students) expressed
difficulty.

I clarified at that time the purpose was NOT to
research difficulties with learning materials.  The
purpose was to see if the 80/20 principle could be
applied as follows: are there areas of frequent
difficulty in a "typical" learning curve for J to
which it would be helpful to give special attention
in any J learning experience and attendant materials?

I have collected the questions and I think some
patterns emerge.  I think there were not enough
respondents to make a "statistically valid"
conclusion.  However, based on the dictum that "no
question too small, nor answer too", here is the list
of difficult areas.  Many of them were from one or
two people, so I have not included survey data.  I
have however freely appended my conclusions.

I hope this is a helpful exercise.  If there is any
further discussion or private messages, I will update
this summary.

PS. NB. Where possible I provided explanations to the
people who asked the questions (via private e-mail).

--RL

==summary follows==

==================================================

1. rows and columns
how and when to apply a function over rows and
columns; what is the relation between this and (f"1
y) and (f"2 y) where y is table.  (general solution
proposed on comp.lang.apl)

2. tacit expressions
when do we best use tacit definition?  (There seems
to be great interest in learning and using this form
of expression, vs. explicit definition) Some
conceptual difficulties expressed.

3. names for primitives
--when and if to use
--current names hard to use
--need list for translation into corresponding terms
in various languages
--desire for categorized list of names
(the author has such a list if desired, also
categorized list of J primitives found in Reiter,
Fractals, Visualization, and J, available thru ISI
and Strand Software)

4. indexing arrays
--how to use "amend" and "item amend", how to index
columns, various boxed subsets, etc.
(Difficulties can be traced to need to understand all
the following concepts before doing this: verbs,
adverbs, rank concepts with nouns (items), and rank
conjunction

5. trains
--hooks and forks not too hard, but the full
capabilities (see table of trains in Dictionary)
presents some conceptual difficulties
--need practice and hints for understanding trains

6. rank
--conceptual problems learning and using rank

7. various questions
--what is the difference between "obverse" and
"adverse"
--what is the difference between "appose" and
"compose"
(perhaps some difficulty here because of similarity
in terminology

8. what is "oblique" and "key" and what are their
purposes
(perhaps some lack of motivational examples in this
case, but those who need these primitives will
probably recognize them immediately)


--how do they work, what are their purposes?
(perhaps some difficulty here bacause of similarity
of symbols)

10. what is relationship of hooks and forks to
"functional composition"

11. some conceptual problems with defining adverbs
and using conjunctions (sorry - no further detail on
this one)

That's the lot for now.

Again, the purpose of this "experiment" (at least for
me) was to gain some insight into J, and also I
thought it would be useful for other learners and
former learners to share their experience.  The J FAQ
and existing documentation deals with many of these
questions.
I concluse this message by noting that There is nothing wrong with any
subject having "difficult spots".

--end of summary



Tue, 02 Dec 1997 03:00:00 GMT  
 
 [ 1 post ] 

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