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Overview¶

ELI has most of the functionality of the ISO APL standard, but it also has facilities not described there such as lists for non-homogeneous data, complex numbers, symbols, temporal data, control structures, scripting files, dictionaries, tables and SQL-like statements. It comes with a compiler for flat array programs. ELI is succinct, easy to learn and versatile. Compared with MATLAB or Python, ELI encourages a dataflow style of programming where the output of one operation feeds the input of another, resulting in greater productivity and clarity of code.

Try ELI¶

ELI is freely available on Windows, Linux and Mac OS; See Download for versions and update information. An introductory paper, a tutorial on Programming with Arrays, ELI for Kids a novel way to learn math and coding, a Primer and a Compiler User's Guide are available in Documents. We give a sample here to illustrate the flavor of the language. People already familiar with APL can jump directly to examine last 3 examples and the APL/ELI Symbol Comparison Table. A line of ELI executes from right to left as a chain of operations; anything to the right of // is a comment. A simple example is given to solve a coin tossing problem (pdf or iBooks) in one line of ELI. Other two sample pieces are computing pi (pdf) and solving a simple data science task (pdf) in ELI.

Examples¶

 !10 //get the vector 1..10
 1 2 3 4 5 6 7 8 9 10

 100*!10 //multiply that vector by 100
 100 200 300 400 500 600 700 800 900 1000

 3 4#!10 //reshape the vector 1..10 into a 3x4 matrix
 1 2 3 4
 5 6 7 8
 9 10 1 2

 &.3 4#!10 //flip the above matrix
 1 5 9
 2 6 10
 3 7 1
 4 8 2

 +/3 4#!10 //sum each row of the 3x4 matrix
 10 26 22

 2*0,!10 //append 0 in front of 1..10, and double it
 0 2 4 6 8 10 12 14 16 18 20
 2*.0,!10 //2 to the power of 0..10
 1 2 4 8 16 32 64 128 256 512 1024

 %1 2 3 5 10 //1 divided by 1 2 3 5 10
 1 0.5 0.3333333333 0.2 0.1

 1024*.%1 2 3 5 10 //1024 takes 1 root, square root, cube root, ..
 1024 32 10.0793684 4 2
 1-2 //1 minus 2
 _1
 _1*.0.5 //square root of minus 1
 0j1
 @1 //pi
 3.141592654
 *.0j1*@1 //eiΠ = -1
 _1

 2012年12月25日+!7 //7 days following Christmas of 2012
 2012年12月26日 2012年12月27日 2012年12月28日 2012年12月29日 2012年12月30日 2012年12月31日 2013年01月01日

 w<-10?.100 //get 10 random numbers from 1..100
 w
 14 76 46 54 22 5 68 94 39 52
 w<50 //compare w with 50
 1 0 1 0 1 1 0 0 1 0
 (w<50)/w //select elements in w which are less than 50
 14 46 22 5 39
 +\(w<50)/w //partial sums of the vector above
 14 60 82 87 126

 $_10+5*!10 //reverse of _10 add to 5 10 .. 50
 40 35 30 25 20 15 10 5 0 _5

 32+1.8*c<-$_10+5*!10 //Fahrenheit correspond to Celsius above
 104 95 86 77 68 59 50 41 32 23
 c,[1.5]32+1.8*c<-$_10+5*!10 //a table of temperature conversion
 40 104
 35 95
 30 86
 25 77
 20 68
 15 59
 10 50
 5 41
 0 32
 _5 23

 (2 3#!6;`ny `ma `md;'ABCDE') //a list of numbers, symbols, chars
 <1 2 3
 4 5 6
 <`ny `ma `md
 <ABCDE
 #"(2 3#!6;`ny `ma `md;'ABCDE') //shape of each element in the list
 <2 3
 <3
 <5 

 D<-(`sym `price `hq:(`appl `ibm `hp `goog;449.1 108.2 24.5 890.3;4 2#'CANYCACA'))
 D
 sym | appl ibm hp goog
 price| 449.1 108.2 24.5 890.3
 hq | 'CANYCACA'
 &.D
 sym price hq
 -------------
 appl 449.1 CA
 ibm 108.2 NY
 hp 24.5 CA
 goog 890.3 CA

 T<-([]sym<-`appl `ibm `hp `goog;price<-449.1 108.2 24.5 890.3;hq<-4 2#'CANYCACA')
 T
 sym price hq
 -------------
 appl 449.1 CA
 ibm 108.2 NY
 hp 24.5 CA
 goog 890.3 CA
 do 'SELECT sym,hq FROM T WHERE price>100'
 sym hq
 -------
 appl CA
 ibm NY
 goog CA
 SELECT successful. 

Symbols¶

APL Keyboard¶

APL/ELI Symbol Comparison¶