J is very crazy programming language, it can solve many problems in one liner.
Also, it is one of the hardest language to read.
Here are good thing about J
J is very easy to install.
J has package manager and you can just one click to install package.
J is very fast language matrix computation and statistic.
J is array language, so list and matrix are very common
Here are the code for J and other languages for doing the same thing.

c =. 3 NB. c is local variable c =: 3 NB. c is global variable !3 NB. 3 factorial -- Haskell fac n | n == 0 = 1 | n > 0 = n * (fac (n-1)) l =. i. 2 NB. create a list = [0, 1, 2] l = [0..2] NB. Haskell {. list NB. head list }. list NB. tail list l =. i:2 NB. list = [-2, -1, 0, 1, 2] l = [-2..2]

APL Symbols

APL symbols is used by the computer language called APL.
Here's a complete list of APL symbols in Unicode.

¯
×
÷
∘
∣
∼
≠
≤
≥
≬
⌶
⋆
⌾
⍟
⌽
⍉
⍝
⍦
⍧
⍪
⍫
⍬
⍭
←
↑
→
↓
∆
∇
∧
∨
∩
∪
⌈
⌊
⊤
⊥
⊂
⊃
⌿
⍀
⍅
⍆
⍏
⍖
⍊
⍑
⍋
⍒
⍎
⍕
⍱
⍲
○

⍳
⍴
⍵
⍺

⍶
⍷
⍸
⍹
⍘
⍙
⍚
⍛
⍜
⍮

¨
⍡
⍢
⍣
⍤
⍥
⍨
⍩

⎕
⍞
⍠
⍯
⍰
⍌
⍍
⍐
⍓
⍔
⍗
⌷
⌸
⌹
⌺
⌻
⌼
⍁
⍂
⍃
⍄
⍇
⍈