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|
Paradigm | array |
---|---|
Designed by | Wai-Mee Ching |
Developer | Hanfeng Chen [2] (Rapidsoft) |
First appeared | 2011 |
Stable release | 0.3 / August 10, 2015 |
Typing discipline | dynamic |
Implementation language | C++, Qt |
Platform | IA-32, x86-64 |
OS | Cross-platform: Windows, Linux, macOS |
License | Freeware |
Filename extensions | .esf .eli |
Website | fastarray |
Influenced by | |
APL, Q |
ELI [3] is an interactive array programming language system based on the programming language APL. It has most of the functions of the International Organization for Standardization (ISO) APL standard ISO/IEC 13751:2001, and also list for non-homogeneous or non-rectangular data, complex numbers, symbols, temporal data, and control structures. A scripting file facility is available to organize programs in a fashion similar to using #include
in C, which also provides convenient data input/output. ELI has dictionaries, tables, and a basic set of SQL-like statements. For performance, it has a compiler restricted to flat array programs.
By replacing each APL character with one or two ASCII characters, ELI retains APL's succinct and expressive way of array programming compared with MATLAB or Python, ELI encourages a dataflow programming style, where the output of one operation feeds the input of another.
ELI is available without charge on Windows, Linux, and macOS.
ELI version 0.3, described as a stable release, was released on August 10, 2015. It integrates with a cross-platform IDE, ELI Studio, which provides a code editor with specialized functions to write and load ELI code. Three added widgets are used to monitor functions, variables, libraries and command history.
Version 0.3 adds several new features. [4]
A line of ELI executes from right to left as a chain of operations; anything to the right of ‘//’ is a comment.
Exclamation point (!) is an interval function. It can generate a vector of n integer from 1 to n.
!10 1 2 3 4 5 6 7 8 9 10
The execution order of ELI is from right to left, and all primitive functions have equal precedence.
5 * 2 + 10 // from right to left, 5 * (2 + 10) 60
In the next example a function add
is declared in a short function form. The arguments of the function can be either a scalar or a vector.
{add: x+y} // short function form add 1 add 2 // 1+2 3 1 add !10 // 1+(1..10) 2 3 4 5 6 7 8 9 10 11
The $
rotation operator returns the reverse order of a vector.
$!10 // reverse 10 9 8 7 6 5 4 3 2 1
A 2-by-3 matrix (or higher dimension array, e.g., 2 3 4#!24
) can be generated by #
with left argument 2 3
.
2 3#!6 // 2 dimension array (matrix) 1 2 3 4 5 6
In first line below the x
is assigned with a vector from 1 to 20. Then, 1 = 2|x
returns odd number True
and even number False
. The /
is a primitive function for compression which picks up the value in x
corresponding to the True
values in its left argument.
x <- !20 // 1..20 x 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 (1 = 2|x) / x // get odd numbers from x 1 3 5 7 9 11 13 15 17 19
Two file extensions are used in ELI for exchanging and sharing code for different purposes: .esf
and .eli
.
An ELI file with extension .esf
is a script file which contains all methods and data. A simple way to create a script file is using the command )out
. However, a clean workspace with no debugging or error information left is needed before a script file can be created. Later the command )fload
can be used to reload the script file.
)out MyScript )lib MyScript.esf )fload MyScript saved 2017.02.17 10:23:55 (gmt-5)
An ELI file with extension .eli
is an ELI workspace file which contains everything in a workspace. save
and load
are commands for workspace files.
)save MyWorkspace )load MyWorkspace saved 2017.02.17 10:57:19 (gmt-5)
APL is a programming language developed in the 1960s by Kenneth E. Iverson. Its central datatype is the multidimensional array. It uses a large range of special graphic symbols to represent most functions and operators, leading to very concise code. It has been an important influence on the development of concept modeling, spreadsheets, functional programming, and computer math packages. It has also inspired several other programming languages.
AWK is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool. It is a standard feature of most Unix-like operating systems.
MATLAB is a multi-paradigm numerical computing environment and proprietary programming language developed by MathWorks. MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages.
Lua is a lightweight, high-level, multi-paradigm programming language designed primarily for embedded use in applications. Lua is cross-platform, since the interpreter of compiled bytecode is written in ANSI C, and Lua has a relatively simple C API to embed it into applications.
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In some programming languages, eval
is a function which evaluates a string as though it were an expression and returns a result; in others, it executes multiple lines of code as though they had been included instead of the line including the eval
. The input to eval
is not necessarily a string; it may be structured representation of code, such as an abstract syntax tree, or of special type such as code
. The analog for a statement is exec
, which executes a string as if it were a statement; in some languages, such as Python, both are present, while in other languages only one of either eval
or exec
is.
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