At one time I briefly spent a bunch of time learning kdb/q. I remember one particular day when I wrote a non-trivial program and it worked first time. I was so shocked I thought I must have suffered some kind of brain aneurism or something.
if you don't mind me asking, do you also remember the day when you wrote some non-trivial program in any language and it "worked" the first time, whatever that means (i presume "correctly")? what was the language? are you sure you've made a full recovery from that shock as well?
on a serious note, APL (and, by proxy, its descendants) invented REPL (dubbed "dialogue approach") long before the people who coined "REPL" even came to be. When that happened, C lanugage wasn't around either. Fortran was, granted, and sure enough it "worked" every time. you didn't even have to try, just punch it up on a punchcard, stick it in, wait a while. done. flawless.
on a closing note: writing correct programs takes skill and happens in iterations. the faster you can iterate, the faster you can justify your money's worth. the less you type, the more you think. less code less bug.
What I mean by "worked" in this context is compiled/parsed[1] without error and had correct behaviour when executed.
I have been programming professionally for about 30 years at this point, so it has happened to me literally hundreds of times at this point in at least 10 other languages- in fact in some languages (especially Haskell and Rust) I would say it's the norm for me rather than the exception to have the code work correctly if it passes compilation (which is sort of the point of strict type systems obviously).
It literally only ever happened the one time in kdb which is why I remember it so vividly and not in those other languages.
I have no idea why you thought your closing note might help, but sure.
>on a serious note, APL (and, by proxy, its descendants) invented REPL (dubbed "dialogue approach") long before the people who coined "REPL" even came to be.
While I have enjoyed learning array languages, and think they are still underrated, Wikipedia seems to disagree with this statement above.
According to wikiepdia, REPL seems to have been coined after Iverson created his notation, but before the first APL was ever written.
Based on the one thing I remember in APL I'm guessing the first two characters are "sum over some data structure" and the data structure is what the next two mean. What does it mean entirely?
APL and K are still pretty daunting, but I've recently been dabbling in Lil[1], which is something like a cross between K and Lua. I can fall back on regular procedural code when I need to, but I appreciate being able to do things like:
127 * sin (range sample_rate)*2*pi*freq_hz/sample_rate
This produces one second audio-clip of a "freq_hz" sine-wave, at the given sample-rate. The "range sample_rate" produces a list of integers from 0 to sample_rate, and all the other multiplications and divisions vectorise to apply to every item in the list. Even the "sin" operator transparently works on a list.
It also took me a little while to get used to the operator precedence (always right-to-left, no matter what), but it does indeed make expressions (and the compiler) simpler. The other thing that impresses me is being able to say:
maximum:if x > y x else y end
...without grouping symbols around the condition or the statements. Well, I guess "end" is kind of a grouping symbol, but the language feels very clean and concise and fluent.
Pretty much, yeah! The difference is that in Python the function that calculates a single value looks like:
foo(x)
...while the function that calculates a batch of values looks like:
[foo(x) for x in somelist]
Meanwhile in Lil (and I'd guess APL and K), the one function works in both situations.
You can get some nice speed-ups in Python by pushing iteration into a list comprehension, because it's more specialised in the byte-code than a for loop. It's a lot easier in Lil, since it often Just Works.
I assume that in most array languages, you also create "words" or however you want to call functions, to reuse code. I wonder about a purely aesthetic issue: how does it look to interleave those symbols with user-defined words that by nature will be much, much longer, i.e. "create-log-entry" or "calculate-estimated-revenue".
I never did any real programming in APL, but I studied it over about 2 months. When you get used to the symbols, reading spelled-out words feels like reading in slow motion, or being stuck in molasses.
Most (not all) APL code I've seen uses very short names, often one letter names, for function names. And APL programmers are famous for cataloging "idiom" which are short phrases for common subroutines. In other words, it's best practice to repeat 3- or 4- symbol phrases instead of defining a subroutine.
Of course, there's nothing about an array language that requires using symbols; but for some reason most do.
>Of course, there's nothing about an array language that requires using symbols; but for some reason most do.
The idioms become words and you read them like words, you don't step through each letter of a word when you read it, you recognize the shape. The same thing happens in APL and its ilk, any commonly used sequence is instantly understood as its function without having to parse each individual symbol and what it does.
> i assume that in most array languages, you also create "words" or however you want to call functions, to reuse code.
sure, that's a very useful feature, like elsewhere.
> I wonder about a purely aesthetic issue: how does it look to interleave those symbols with user-defined words that by nature will be much, much longer, i.e. "create-log-entry" or "calculate-estimated-revenue".
strictly speaking, dashes and underscores in k can't even be a part of identifier - they are core language primitives. it is very uncommon to see java-like identifiers like CalculateEstimatedRevenue, why would you want that?
to your question:
here's a bit of an oddity: all user-defined functions and core language operators can be called using functional notation:
v:1 2 3 / some vector
v+v / usual infix notation, two operands: left and right
2 4 6
+[v;v] / same as infix, but called as it were a function.
2 4 6
add:{x+y} / a user-defined function: a lambda with a name and two operands.
add[v;v]
2 4 6
but there is an important distinction between the two. you can't use your `add` function infix, you must call it as a function, and there are good reasons for that:
2 add 2 / that's not gonna work
that said, mixing language primitives with function calls looks and reads just fine:
How does that scale up to program that's thousands of lines? What if you have a hundred different vectors? You're not going to be calling them v1, v2, ...
Or, do you just not do that sort of stuff in these languages? I'm not very familiar with them, but I have ended up with some pretty long programs using Pandas in Python.
Perhaps a more precise question is whether you can write programs as performant as those written in C or Fortran and the answer is it depends on the program (and more likely the programmer). The languages tend to do memory management for you which means giving up some control. Most use “immutable” data structures which force more contraints.
But for the loss of control you get stuff like fancy SIMD implementation for nothing.
All and all there’s a cost/benefit calculation but that ratio can get quite low.
this is a gross undeappreciation of a truly remarkable effort by my dear friend and associate. also, at least one of the languages presented is due to him. you can call him @ktye. he's too modest.
it is not a Kunstkamera or some computer cryptozoology extravaganza. many things are shown here, from different eras, but some are not - they are evolving. and progress takes sacrifice.
cheers
k.
ps. we usually spell atw as atw :) he also goes by a. don't chicken out, send him an email. he's a very friendly guy. just like me.
Yeah - IDK why it never makes it to these lists. R too. Matlab being 2D matrix first/default gets it right for me there. IK matrices trivially translate to arrays, still: find 2D to be extra expressive on human level, for zero price paid. I get it it's all the same to the cpu. 2D rows-columns rectangle of data being the simplest data structure both necessary and sufficient covering a 1) matrix 2) spreadsheet 3) SQL table 4) directed graph of nodes and edges. (in the past I've read someplace that lists are for pie eaters, but wouldn't know myself
Octave covers all the Matlab functionality I need, not sure if it runs in a browser. I mean if you have the source code for something there must be some way to get it to run in a browser these days, right?
Programming in an array lang "should" generally feel like using a calculator.
You are working in a REPL, starting with small expressions to verify they are roughly doing what you want and then composing them to build up until you can plug it all together and now have a formula you can plug into the calculator to plug and chug all the rest of your data.
So in that sense yeah it does kind of replicate the magic of the first time you got a complex equation or BASIC program to run on your TI back in your school days.
R is also an array language, but a non-iversonian one. Another good ressource for array languages is https://aplwiki.com/.
r/apljk on reddit is also active.
That's my understanding too. R never seems to make these lists.
numpy is also an array language, with a userbase that of (R+k)^10
never seems to make these lists :)
At one time I briefly spent a bunch of time learning kdb/q. I remember one particular day when I wrote a non-trivial program and it worked first time. I was so shocked I thought I must have suffered some kind of brain aneurism or something.
oh, gosh. sorry for your loss.
if you don't mind me asking, do you also remember the day when you wrote some non-trivial program in any language and it "worked" the first time, whatever that means (i presume "correctly")? what was the language? are you sure you've made a full recovery from that shock as well?
on a serious note, APL (and, by proxy, its descendants) invented REPL (dubbed "dialogue approach") long before the people who coined "REPL" even came to be. When that happened, C lanugage wasn't around either. Fortran was, granted, and sure enough it "worked" every time. you didn't even have to try, just punch it up on a punchcard, stick it in, wait a while. done. flawless.
on a closing note: writing correct programs takes skill and happens in iterations. the faster you can iterate, the faster you can justify your money's worth. the less you type, the more you think. less code less bug.
does that help?
What I mean by "worked" in this context is compiled/parsed[1] without error and had correct behaviour when executed.
I have been programming professionally for about 30 years at this point, so it has happened to me literally hundreds of times at this point in at least 10 other languages- in fact in some languages (especially Haskell and Rust) I would say it's the norm for me rather than the exception to have the code work correctly if it passes compilation (which is sort of the point of strict type systems obviously).
It literally only ever happened the one time in kdb which is why I remember it so vividly and not in those other languages.
I have no idea why you thought your closing note might help, but sure.
[1] Depending on language obviously.
>on a serious note, APL (and, by proxy, its descendants) invented REPL (dubbed "dialogue approach") long before the people who coined "REPL" even came to be.
While I have enjoyed learning array languages, and think they are still underrated, Wikipedia seems to disagree with this statement above.
According to wikiepdia, REPL seems to have been coined after Iverson created his notation, but before the first APL was ever written.
https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93prin...
4 replies →
I know you! We worked together for a MF at GS.
Hey there. Hope you’re doing well. Last I heard of him he was doing some sort of real-estate thing in Japan.
1 reply →
Array languages are such a mind twist and so fun. I dabbled in J at one point, and I love explaining
+/%#
to people. But the real expressive power comes when you start to get into tacit expressions yourself, understand function exponents, and "get" under.
Hmmm... maybe I need a refresher...
There's an APK, for dabbling on the phone at times when there's no larger computer available but still time to spend.
https://code.jsoftware.com/wiki/Guides/JAndroid
Having J on the phone in your pocket is great.
And lots of the "labs" (interactive tutorials) are built in too: 3 dots -> Help -> Labs..
Edit: I should also have mentioned that Termux on android can build ngn-k, goal and a bunch of other open source array languages too.
There's also Rob Pike's Ivy language for Android too.
1 reply →
> I love explaining +/%#
Based on the one thing I remember in APL I'm guessing the first two characters are "sum over some data structure" and the data structure is what the next two mean. What does it mean entirely?
avg=: +/ % #
+/ sums the items of the array.
# counts the number of items in the array.
% divides the sum by the number of items.
13 replies →
APL and K are still pretty daunting, but I've recently been dabbling in Lil[1], which is something like a cross between K and Lua. I can fall back on regular procedural code when I need to, but I appreciate being able to do things like:
This produces one second audio-clip of a "freq_hz" sine-wave, at the given sample-rate. The "range sample_rate" produces a list of integers from 0 to sample_rate, and all the other multiplications and divisions vectorise to apply to every item in the list. Even the "sin" operator transparently works on a list.
It also took me a little while to get used to the operator precedence (always right-to-left, no matter what), but it does indeed make expressions (and the compiler) simpler. The other thing that impresses me is being able to say:
...without grouping symbols around the condition or the statements. Well, I guess "end" is kind of a grouping symbol, but the language feels very clean and concise and fluent.
[1]: https://beyondloom.com/decker/lil.html
I assume this is the same as this?
For that matter,
6 replies →
Pretty much, yeah! The difference is that in Python the function that calculates a single value looks like:
...while the function that calculates a batch of values looks like:
Meanwhile in Lil (and I'd guess APL and K), the one function works in both situations.
You can get some nice speed-ups in Python by pushing iteration into a list comprehension, because it's more specialised in the byte-code than a for loop. It's a lot easier in Lil, since it often Just Works.
3 replies →
I assume that in most array languages, you also create "words" or however you want to call functions, to reuse code. I wonder about a purely aesthetic issue: how does it look to interleave those symbols with user-defined words that by nature will be much, much longer, i.e. "create-log-entry" or "calculate-estimated-revenue".
I never did any real programming in APL, but I studied it over about 2 months. When you get used to the symbols, reading spelled-out words feels like reading in slow motion, or being stuck in molasses.
Most (not all) APL code I've seen uses very short names, often one letter names, for function names. And APL programmers are famous for cataloging "idiom" which are short phrases for common subroutines. In other words, it's best practice to repeat 3- or 4- symbol phrases instead of defining a subroutine.
Of course, there's nothing about an array language that requires using symbols; but for some reason most do.
>Of course, there's nothing about an array language that requires using symbols; but for some reason most do.
The idioms become words and you read them like words, you don't step through each letter of a word when you read it, you recognize the shape. The same thing happens in APL and its ilk, any commonly used sequence is instantly understood as its function without having to parse each individual symbol and what it does.
2 replies →
> i assume that in most array languages, you also create "words" or however you want to call functions, to reuse code.
sure, that's a very useful feature, like elsewhere.
> I wonder about a purely aesthetic issue: how does it look to interleave those symbols with user-defined words that by nature will be much, much longer, i.e. "create-log-entry" or "calculate-estimated-revenue".
strictly speaking, dashes and underscores in k can't even be a part of identifier - they are core language primitives. it is very uncommon to see java-like identifiers like CalculateEstimatedRevenue, why would you want that?
to your question:
here's a bit of an oddity: all user-defined functions and core language operators can be called using functional notation:
but there is an important distinction between the two. you can't use your `add` function infix, you must call it as a function, and there are good reasons for that:
that said, mixing language primitives with function calls looks and reads just fine:
hope this helps!
How does that scale up to program that's thousands of lines? What if you have a hundred different vectors? You're not going to be calling them v1, v2, ...
So does it end up as
Or, do you just not do that sort of stuff in these languages? I'm not very familiar with them, but I have ended up with some pretty long programs using Pandas in Python.
3 replies →
It depends on the language and the programmer.
https://github.com/mlochbaum/BQN/blob/master/vm.bqn
This is cool. Wish there was more examples for jtye/k so I would have a better chance of learning to use it.
Also missing Uiua.
This is wonderful: APL is there! And a visual APL keyboard too.
Dumb question from an outsider: are array languages competitive with something like C or Fortran in their niche performance-wise?
> are array languages competitive with something like C or Fortran
The REPL is what matters - also while being performant.
Someone asks you a question, you write something, you run it and say an answer, the next question is asked etc.
I've seen these tools be invaluable in that model, over "write software, compile and run a thousand times" problems which C/Fortran lives in.
Perhaps a more precise question is whether you can write programs as performant as those written in C or Fortran and the answer is it depends on the program (and more likely the programmer). The languages tend to do memory management for you which means giving up some control. Most use “immutable” data structures which force more contraints.
But for the loss of control you get stuff like fancy SIMD implementation for nothing.
All and all there’s a cost/benefit calculation but that ratio can get quite low.
Today I learned that there is such a thing as an array language! This is so neat! Need to learn all of them.
Start here: https://xpqz.github.io/learnapl
or here:
https://xpqz.github.io/kbook
Is this written by Arthur Whitney himself?
The zoo is a collection of web interfaces to a number of array languages written by several people including ATW.
this is a gross undeappreciation of a truly remarkable effort by my dear friend and associate. also, at least one of the languages presented is due to him. you can call him @ktye. he's too modest.
it is not a Kunstkamera or some computer cryptozoology extravaganza. many things are shown here, from different eras, but some are not - they are evolving. and progress takes sacrifice.
cheers k.
ps. we usually spell atw as atw :) he also goes by a. don't chicken out, send him an email. he's a very friendly guy. just like me.
no uiua :(
Uiua is the first one that made array languages "click" for me due to the formatter.
Came here to say the same thing. Uiua is my favorite language by far. BQN is also a cool "Nu-APL" but Uiua is just a full generation ahead.
What makes Uiua a full generation ahead of BQN?
It's missing Nial I think.
i'm sure niall is missing it too :)
what does he do these days?
MATLAB is an array language.
Yeah - IDK why it never makes it to these lists. R too. Matlab being 2D matrix first/default gets it right for me there. IK matrices trivially translate to arrays, still: find 2D to be extra expressive on human level, for zero price paid. I get it it's all the same to the cpu. 2D rows-columns rectangle of data being the simplest data structure both necessary and sufficient covering a 1) matrix 2) spreadsheet 3) SQL table 4) directed graph of nodes and edges. (in the past I've read someplace that lists are for pie eaters, but wouldn't know myself
MATLAB doesn't even have 1-d arrays, it really is missing the principled and composable operations that make array languages useful
I believe the ArrayCast had this debate on whether it's considered an arraylang when they had some of the MATLAB devs on.
The determination they came to was that MATLAB is an array lang but not an iversonian array lang.
1 reply →
MATLAB doesn't have a FOSS implementation that runs in a browser.
Octave covers all the Matlab functionality I need, not sure if it runs in a browser. I mean if you have the source code for something there must be some way to get it to run in a browser these days, right?
1 reply →
it is one of their cousins
i made a site for trying out the jtye/k version, since it was missing from the zoo: https://mao-syseng.github.io/k-playground/
coming from javascript world this is super interesting, i will try and document some of the stuff i learn on that site is well.
I once took a graduate course from Larry Snyder on ZPL. I found it pretty neat because it made communication costs very easy to reason about.
Array languages: where your first working program feels like a happy accident.
Programming in an array lang "should" generally feel like using a calculator.
You are working in a REPL, starting with small expressions to verify they are roughly doing what you want and then composing them to build up until you can plug it all together and now have a formula you can plug into the calculator to plug and chug all the rest of your data.
So in that sense yeah it does kind of replicate the magic of the first time you got a complex equation or BASIC program to run on your TI back in your school days.
> your first working program feels like a happy accident.
if you don't mind sharing: how did your own first working program felt like, and what was it written in?
by the way, did it work, or did it work correctly? it's a small but important distinction.
[dead]
[flagged]