J programming language
Hacker ApprovedThe most recommended of 7 array programming languages
People recommend J for its terse array-based syntax, free open-source implementation and learning materials; critics find its tacit syntax and symbols hard to learn and remember.
People recommend J for its terse array-based syntax, free open-source implementation and learning materials; critics find its tacit syntax and symbols hard to learn and remember.
33 people gave an opinion
- recommend it
- 23
- criticize it
- 10
- approval share
- 70%
Recommended in 8 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: not recommended
- July 2026: not recommended
- August 2026: not recommended
- September 2026: not recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 23 people recommend itNeeds 10 or more, met.
- 2.3 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 8 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Terse, short code
“I still love the atoms and terseness of array languages and writing close to the metal.”
Comment from 16 Feb 2026 in “planckforth: Bootstrapping a Forth interpreter from hand-written tiny ELF binary” “I very appreciate this language for shortness but this kind of shortness might annoy.”
Comment from 12 Jan 2026 in “Which programming languages are most token-efficient?” “The J answers tend to be very short and very fast.”
Comment from 14 Dec 2025 in “An Implementation of J (1992)” - Comment from 14 Dec 2025 in “An Implementation of J (1992)”
Free with extensive learning materials
“J is FOSS, J has extensive learning materials, and J is reasonably batteries-included”
Comment from 22 Jan 2026 in “In Praise of APL (1977)” “The intro books for J are great for working through math and learning J”
Comment from 13 Apr 2026 in “The APL Programming Language Source Code (2012)” Powerful for number-crunching
“J is for number munching, Lisp is for everything else.”
Comment from 24 Jan 2026 in “Ask HN: Weekend Social: Top two programming languages and what they can borrow?” “it would be hard to make the case that it lacks power”
Comment from 14 Dec 2025 in “An Implementation of J (1992)” Gentle learning curve
“A few nights playing with J and learning was enough to not be completely lost and able to make some progress, but it is still a challenge.”
Comment from 14 Dec 2025 in “An Implementation of J (1992)” “its learning curve isn't steep”
Comment from 22 Jan 2026 in “In Praise of APL (1977)”
What people warn about
Each mark is one comment
Dense syntax hard to read
“the end result is that my solutions become too alien for the general practitioner”
Comment from 27 Jul 2026 in “Introduction to Data-Oriented Design [pdf]” “I find it worse to use single letter names for functions”
Comment from 14 Dec 2025 in “Perl's decline was cultural” “this syntax is almost as bad as that of TypeScript”
Comment from 15 Dec 2025 in “An Implementation of J (1992)” - Comment from 14 Dec 2025 in “An Implementation of J (1992)”
Poor fit for databases and apps
“it has been made mostly for math so it is not optimized for CRUDs”
Comment from 4 Jan 2026 in “Ask HN: What if a language's structure determined memory lifetime?” “they cannot be used with sql databases or existing python libraries”
Comment from 28 Sep 2026 in “Evolving programming languages in the AI era” “It may be not efficient at all for using rich types and structs”
Comment from 4 Jan 2026 in “Ask HN: What if a language's structure determined memory lifetime?”
Other array programming languages people recommend
The four most recommended other array programming languages, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| J programming languageThis page | 23 | 10 | 70% | 8 | — | Approved |
| Uiua | 20 | 4 | 83% | 9 | — | Approved |
| BQN | 11 | 2 | 85% | 8 | — | Approved |
| K programming language | 11 | 5 | 69% | 5 | — | Approved |
| kdb+ q | 7 | 1 | 88% | 5 | — | — |
What people said
36 of the 37 comments that mention it, newest first. Each links to the original comment.
“J is elegant enough, but I feel like I'd rather try this in a Scheme dialect”
“There are nice APL- and J-based math books with this approach.”
“they cannot be used with sql databases or existing python libraries”
“the end result is that my solutions become too alien for the general practitioner”
“There's a reason they're not more popular...”
“J has a pretty active community, or at least used to.”
“It’s much faster to type the code than explain everything to AI.”
“The intro books for J are great for working through math and learning J”
“I hear you for the complexities in J though.”
“It has a larger vocabulary than most array languages, which I felt made it hard to learn.”
“I still love the atoms and terseness of array languages and writing close to the metal.”
“J is for number munching, Lisp is for everything else.”
“its learning curve isn't steep”
“J is FOSS, J has extensive learning materials, and J is reasonably batteries-included”
“J meets all those requirements.”
“Personally I find the custom symbols of APL and BQN to be easier to type and read than the ASCII of J and K.”
“I very appreciate this language for shortness but this kind of shortness might annoy.”
“Not surprisingly, it is J, an APL dialect.”
“It may be not efficient at all for using rich types and structs”
“it has been made mostly for math so it is not optimized for CRUDs”
“this syntax is almost as bad as that of TypeScript”
“Terse languages are the best”
“I find it worse to use single letter names for functions”
“feels like a breath of fresh air from the usual LLM slop”
“The J answers tend to be very short and very fast.”
“Oh yea, J sources, the nightmare fuel”
“It's very non-ideal for the curious autodidacts.”
“it would be hard to make the case that it lacks power”
“There's a lot to love in the APLs even you ultimately don't buy the fanboy arguments”
“The tacit syntax is too idiosyncratic (I always forget the different types of verb trains)”
“2.5 decades of rock solidness”
“A few nights playing with J and learning was enough to not be completely lost and able to make some progress, but it is still a challenge.”
“I'm already lost, and this is the first example.”
“I highly recommend giving it a try in a language you don't know, it's fun!”
“J kind of broke my brain and it never became natural to me.”
“It’s probably more accessible than APL since its symbols can be found on conventional keyboards.”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.