athas / array-language-comparisons

A comparison of array languages: APL, J, BQN, Q, Julia, R, NumPy, Nial, Futhark & SaC.

This is a collection of idioms and small programs in APL, J, BQN, Julia, R and NumPy.

There are several sites that do these kinds of comparisons:

General

• Rosetta Code
• Programming-Idioms

Array Language Specific

• BQN-Dyalog Dictionary
• BQN-J Dictionary
• J-Dyalog APL Rosetta

Language / Library Websites

	Language	Main Website	Help / Docs	Online REPL
💚	Dyalog APL	dyalog.com	Dyalog Help	TryAPL
💚	J	jsoftware.com	J NuVoc	J Playground
💚	BQN	mlochbaum.github.io/BQN	BQN Docs	BQNPAD
💚	Q	code.kx.com/q	Q Ref	🚫
💙	Julia	julialang.org	Julia Docs	Replit
💙	NumPy*	numpy.org	NumPy Docs	Replit
💙	R	r-project.org	R Docs	JDoodle
💜	Nial	nial-array-language.org	Nial Dictionary	TIO
💜	Futhark	futhark-lang.org	Futhark Docs	🚫
💜	SaC	sac-home.org	SaC Docs	🚫

* Library, not an actual language

• 💚 Main (APL-Family) Array Languages
• 💙 Main (Non-APL-Family) Array Languages
• 💜 Fringe Array Languages

Comparisons

1. REPL
2. Index Base
3. Length of Array (Leading Axis)
4. Shape of Array
5. Number of Elements in Array

	1	2	3	4	5
APL	🟢	1 (or ⎕IO)	≢	⍴	×/⍴
J	🟢	0	#	$	*/@$
BQN	🟢	0	≠	≢	×´≢
Q	🟡	0	count	🚫	count raze
Julia	🟢	1	size(a, 1)	size(a)	length(a)
NumPy	🟢	0	len(a)	a.shape	a.size
R	🟢	1	dim(a)[1]	dim(a)	length(a)
Nial	🟡	0	first shape	shape	tally
Futhark	🟡	0	length	🚫	flatten |> length
SaC	🚫	0	shape(a)[0]	shape(a)	prod(shape(a))

🟡 Means the REPL has limitations

• Q REPL has no HOME, END, or any arrows (CTRL or not)
• Nial REPL has no CTRL left or right arrow
• Futhark REPL has no HOME, END, or DEL

If you are using Q, Nial, Futhark or other languages with REPL limitations, you can get around this by invoking with rlwrap. On Linux using the Q REPL:

sudo apt install rlwrap
rlwrap taskset -c 0 ./q

Other Comparisons

1. Creating an Identity Matrix
2. Creating an Iota Matrix
3. Reversing a Matrix Row-wise and Column-wise