The complaint isn't "a program like that can't be written", or the
argument would be that J isn't even Turing complete. The complaint
is "I can't write a program like that in the manner I'd like."
Quotes:
* No non-array data structures: hash tables, trie, graphs, etc. This
is a show stopper because so many problems are easier to reason about
and to solve by picking a more suitable data structure.
I reason about those things in terms of mathematics and abstract
structures: I'd venture to say that's par for the course because its
easiest.
Suppose you want to translate a program you've written in a non-APL
language into J. Much of the program can simply be transliterated,
page-into-sentence, without much concern for the overall design
of either program... unless a non-array data structure is very
important. Now you have to think about how precisely the original
program is using the data structure and how you can do that in some
other way in J.
The same speedbump shows up if you're following a tutorial, or trying
to implement an algorithm according to a book or paper's description:
as soon as a non-array data structure's properties become important,
there's an abrupt increase in the difficulty of your task and of
the depth of understanding of the problem domain that's required of
you.
The abruptness is off-putting all by itself. Imagine a language where
+ - * are all available but % isn't and the response to wanting it is
1. have you considered solving your problem without division? It's
very expensive! With a constant denominator and fixed-width integers
it's even possible to divide *with* multiplication by a magic number.
2. you can implement it yourself (with unusually bad performance)
3. you can get it from the FFI
4. is this so weird? ARM processors don't have % instructions.
Yeah, it's pretty weird. Not having hash tables has also become weird.
On 2021-04-14 05:25, ethiejiesa via Programming wrote:
It's not J, but FWIW Dyalog APL apparently can boast this realistic,
immersive simulation of some piece of Finnish coastline. The 3D
engine is an external dependency, but supposedly everything else is
straight APL:
https://www.dyalog.com/case-studies/simulation.htm
Since the core of that project is taking large amounts of data,
scattered in lots of non-uniform formats, and munging it into a
concrete realtime visualization, you might find it
interesting/inspiring/helpful/whatever.
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