Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/benzap/eden

Embedded and Extensible Scripting Language in Clojure
https://github.com/benzap/eden

clojure clojurescript eden lua programming-language

Last synced: about 2 months ago
JSON representation

Embedded and Extensible Scripting Language in Clojure

Awesome Lists containing this project

README 

        
#+TITLE: Eden - lua-based scripting language in clojure

#+AUTHOR: Benjamin Zaporzan

#+DATE: 2018-07-01

#+EMAIL: [email protected]

#+LANGUAGE: en

#+OPTIONS: H:2 num:t toc:t \n:nil ::t |:t ^:t f:t tex:t



[[https://travis-ci.org/benzap/eden][https://travis-ci.org/benzap/eden.svg?branch=master]]



[[https://clojars.org/eden][https://img.shields.io/clojars/v/eden.svg]]



[[./doc/logo.png]]



*eden* is a language akin to traditional scripting languages like lua,

python or ruby. It is embeddable, extensible, sandboxed, and

familiarly simple.



*eden* is unique, in that it uses only valid EDN data values for data

representation. This has the added benefit of ridiculously easy

clojure interoperability.



/eden is still in beta development, so things are going to be broken,

undocumented, and error messages are close to non-existent./



#+BEGIN_SRC

  (require '[eden.core :as eden])



  (eden/eval println("Hello World!"))

  ;; Hello World!

  ;;



  (eden/eval

   local x = 2 + 2



   function add2(x)

     return x + 2

   end



   println("The value of x plus 2 equals" add2(x)))

  ;; The value of x plus 2 equals 6

  ;;



#+END_SRC



Almost all of clojures core libraries work out-of-the-box within eden



#+BEGIN_SRC



  (eden/eval println(rest([1 2 3 4]))) ;; (2 3 4)



  (eden/eval println(conj([1 2 3] 4))) ;; [1 2 3 4]



  (eden/eval

   local x = list(1 2 3 4)

   for i in x do

     println(i)

   end)

   ;; 1

   ;; 2

   ;; 3

   ;; 4



#+END_SRC



Even higher-level clojure functions work in eden



#+BEGIN_SRC



  (eden/eval

   local result = map(inc vector(1 2 3 4))

   println(result))

  ;; (2 3 4 5)



  (eden/eval

   local sum = reduce(function(a b) return a + b end list(1 2 3 4))

   println(sum))

  ;; 10



#+END_SRC



Functions written in *eden* can be used within clojure



#+BEGIN_SRC



  (eden/eval

   function addfirst2(xs)

     return first(xs) + second(xs)

   end)



  (def addfirst2 (eden/get-var 'addfirst2))

  (println (addfirst2 [1 2 3 4]))

  ;; 3



#+END_SRC



Functions written in clojure can be used within *eden*

 

#+BEGIN_SRC



  (defn hello [name]

    (str "Hello " name "!"))



  (eden/set-var! 'hello hello)

  (eden/eval hello("Ben")) ;; "Hello Ben!"



#+END_SRC



*eden* uses dot notation for retrieving and assigning to EDN

collections, like vectors and hash maps.



#+BEGIN_SRC



  (eden/eval

   local person = {}

   person.first-name = "John"

   person.last-name = "Doe"

   person.age = 12

   println(person))

  ;; {:first-name John, :last-name Doe, :age 12}



  ;;

  ;; similarly, vectors can be accessed using square bracket notation

  ;;



  (eden/eval

   local list-of-letters = ["a" "b" "c"]

   println(list-of-letters[1])) ;; b



#+END_SRC



The getter syntax makes it much easier to manipulate more complex

collections.



#+BEGIN_SRC



  (eden/eval

   local default-person = {}

   default-person.first-name = "John"

   default-person.last-name = "Doe"



   local display = function(p)

     println(p.first-name "-" p.last-name)

   end



   local person-list = [

     default-person

     default-person

   ]



   person-list[0].first-name = "Ben"

   person-list[0].last-name = "Z"

   person-list[1].first-name = "Jane"

   person-list[1].last-name "M"



   println(person-list)

   display(person-list[0]))

   ;; [{:first-name Ben, :last-name Z} {:first-name Jane, :last-name Doe}]

   ;; Ben - Z



#+END_SRC



* Rationale



  *eden* was developed to be a embedded language within a natively

  compiled clojure application (GraalVM'a native-image). It can be

  used to expose the application API so that a userbase can create

  plugins in a sandboxed environment. The applications of *eden*

  within clojure are very similar to the applications of lua within

  c/c++.



  *eden* can also be used as a standalone scripting language. A

  natively compiled commandline tool has been developed, and can be

  used to manipulate EDN files similar to how you would implement JSON

  files in javascript. Everything is still in its early stages, so I

  would not recommend using it in a production setting.



  I also plan on compiling *eden* to clojurescript, although the

  applications of eden within clojurescript are not of interest to me

  at the moment.



* Requirements

  

  *eden* requires clojure 1.9+



* Installation

** Native Executable

   Native Executables can be found on the [[https://github.com/benzap/eden/releases][releases page]]

   

   There are currently native executables generated for debian-based

   linux systems, and for rpm-based systems.



   If you would like to generate your own native executable, please

   follow the configuration instructions included in the Makefile.



   An example use:



   #+BEGIN_SRC sh

   $ eden -e "println(\"Hello World!\")"

   Hello World!

   $

   #+END_SRC



   #+BEGIN_SRC

   ;; hello.eden



   function hello(name)

     return str("Hello " name "!")

   end



   local name = system.args[0] or "there"

   println(hello(name))

   #+END_SRC



   #+BEGIN_SRC sh

   $ eden hello.eden ben

   Hello ben!

   #+END_SRC



** Uberjar

   Alternatively, the uberjar can be found on the [[https://github.com/benzap/eden/releases][releases page]], which

   can be run as follows with ~java~



   #+BEGIN_SRC sh

   java -jar eden--standalone.jar 

   #+END_SRC



** Clojure Installation



   For the latest version, please visit [[https://clojars.org/eden][clojars.org]]



   *Leiningen/Boot*

  

  #+BEGIN_SRC clojure



  [eden "0.9.0"]



  #+END_SRC



   *Clojure CLI/deps.edn*



  #+BEGIN_SRC clojure



  eden {:mvn/version "0.9.0"}



  #+END_SRC



   *Gradle*



  #+BEGIN_SRC groovy



  compile 'eden:eden:0.9.0'



  #+END_SRC



   *Maven*



  #+BEGIN_SRC xml



  

    eden

    eden

    0.9.0

  



  #+END_SRC



** Docker Image Execution

   If you wish to just try out *eden*, and you have docker installed,

   give this a shot:



   #+BEGIN_SRC

   $ docker run --rm -ti benzap/eden:0.8.0-1 -e '"Hello Eden!"'

   #+END_SRC



   Using *eden* with docker has its issues, as you have to mount

   volumes in order to execute scripts. Here is a small example, which

   mounts my current working directory under the volume */mount*, so

   that it can execute an eden script that also resides in my current

   working directory.



   #+BEGIN_SRC

   $ docker run --rm -v `pwd`:/mount -ti benzap/eden:0.8.0-1 /mount/my_script.eden

   #+END_SRC

* Introduction



  *eden* is an imperative language, so it embraces the idea of mutable

  values being passed around. However, *eden* re-uses the persistent

  data collections that make up clojure, which makes eden

  copy-on-write when performing operations on collections.



  #+BEGIN_SRC



  function people-eq?(p1 p2)

    if p1 == p2 then

      println("Are Equal!")

    else

      println("Not Equal!")

    end

  end



  local person1 = {:first-name 12 :age 12}

  local person2 = person1



  people-eq?(person1 person2) ;; Are Equal!



  person2.age = 13



  people-eq?(person1 person2) ;; Not Equal!



  #+END_SRC



  In a more traditional language like lua, ~person2~ would hold a

  reference to the same data structure as ~person1~. However, *eden*

  uses copy-on-write semantics. They never share a reference. If you

  want to share a reference between variables, use a clojure atom.



  #+BEGIN_SRC



  local person1 = atom({:first-name "Ben" :age 12})

  local person2 = person1

                

  swap!(person2 function(p) p.age = 13 return p end)

  println(deref(person1)) ;; {:first-name Ben, :age 13}



  #+END_SRC



* Installing the Eden Console for Administrative Tooling



  *eden* can be run from the commandline, which can make it suitable

  for commandline scripting. It can evaluate expressions

  with the -e commandline flag, or can evaluate files, which are

  usually designated with the suffix *.eden.



  The easiest way to try out *eden* is to clone the project and run it

  within the project directory.



  #+BEGIN_SRC sh

  $ git clone https://github.com/benzap/eden.git

  $ cd eden

  $ lein run ./examples/eden/get_project_version.eden

  0.8.0

  #+END_SRC



** Debian Installation

   Tested in Ubuntu 17.10, 18.10.

   

   /May require stdc++ lib dependencies for other distributions./

   

   #+BEGIN_SRC

   wget https://github.com/benzap/eden/releases/download/0.8.0/eden-0.8.0-amd64.deb

   sudo dpkg -i eden-0.8.0-amd64.deb

   #+END_SRC



** Redhat Installaion

   Tested on Fedora 28

   

   #+BEGIN_SRC

   wget https://github.com/benzap/eden/releases/download/0.8.0/eden-0.8.0-1.x86_64.rpm

   sudo rpm -i eden-0.8.0-1.x86_64.rpm

   #+END_SRC



** Running the standalone uberjar

   Grab a pre-generated uberjar from the [[https://github.com/benzap/eden/releases][releases page]], and run it directly:



  #+BEGIN_SRC



  $ java -jar eden-0.8.0-standalone.jar ./examples/eden/basic_http_server.eden



  #+END_SRC



  The best use of *eden* as a standalone tool is to either build your

  own native executable, or grab one of the pre-compiled ones provided

  on the [[https://github.com/benzap/eden/releases][releases page]]



** Installing on Windows

   *experimental*



   Download the *.exe from the [[https://github.com/benzap/eden/releases][releases page]]



   /Note: Has issues with the current working directory, *.jar recommended/



* Programming in Eden

  This is a short manual explaining the Eden programming language.

** Values and Types

   Eden is a /dynamically typed/ language based on data types provided

   in the [[https://github.com/edn-format/edn][EDN data format]]. The types include:



   * Integers / BigIntegers :: ~0~, ~13~, ~-13~, ~14N~

   * Floats / Doubles :: ~3.14~, ~10e+3~

   * Strings :: ~"Hello"~

   * Keywords :: ~:foo~, ~:bar~

   * Booleans :: ~true~, ~false~

   * Symbols (vars) :: ~x~, ~y~

   * Lists :: ~list(1 2 3)~, ~list(4 5 6)~

   * Vectors :: ~[1 2 3]~, ~vector(1 2 3)~

   * Maps :: ~{:a 123 :b 456}~

   * Set :: ~#{:a :b :c}~, ~set(:a :b :c)~

   * Nil :: ~nil~



   I encourage you to review the EDN data format for additional types

   you might experience when using Eden.



** Variables

   Variables in Eden are presented in the form of Symbols. The extent

   of allowed variable names consists of what is allowed in the EDN

   format, but also restricts you from using keywords used by the Eden

   language, and symbols beginning with a dot (ex. ~.name ~.foo),

   since this is used to access collection properties.



   #+BEGIN_SRC

   ;; Allowed



   x y foo bar is-value? set-value! $hallo



   ;; Not Allowed



   for in .foo .bar end

   #+END_SRC



** Statements

*** Assignment

    Assignment in Eden is similar to languages like lua, or

    python. The most basic form of assignment is assigning a value to

    a global variable:



    #+BEGIN_SRC

     = 



    x = 12

    foo = :bar

    chk? = false

    #+END_SRC



    Global variables live for the duration of the program, and can be

    accessed from anywhere in the program.



    The second form of assignment is assigning to a local variable:



    #+BEGIN_SRC

    local  = 

    

    local x = 12

    local foo = :bar

    local chk? = false

    #+END_SRC



*** Conditional Structure

    The first and most often used control structure is the ~if~

    control structure:



    #+BEGIN_SRC

    ;; if structure

    if  then

      

    end



    ;; if-else structure

    if  then

      

    else

      

    end



    ;; if-elseif-else structure

    if  then

      



    elseif  then

      



    [elseif  then

      ]...



    else

      

    end

    #+END_SRC



    Examples



    #+BEGIN_SRC

    local age = 12

    if age < 21 then

      println("You are underage")

    end



    chk? = true

    if chk? then

      println("Value is true")

    else

      println("Value is false")

    end

    #+END_SRC



*** While Statement

    While statements check its condition, and upon determining that

    it's true, will run the block of statements contained in its

    body. Each time, it will check the condition and call the statment

    block forever until the condition becomes false.



    #+BEGIN_SRC

    while  do

      

    end

    #+END_SRC



    Examples



    #+BEGIN_SRC



    ;; keep looping until `i` is greater than or equal to 10

    local i = 0

    while i < 10 do

      println("i: " i)

      i = i - 1

    end    



    ;; this will loop forever

    while true do

      println("Never gonna give you up")

    end



    #+END_SRC



*** Repeat-Until Statement

    Repeat statements are similar to the while statement, with the

    differences being that the body is guaranteed to always be called

    at least once, and the body will be looped over only if the

    condition is false.

    #+BEGIN_SRC

    repeat

      

    until 

    #+END_SRC



    Examples



    #+BEGIN_SRC

    



    ;; keep looping until 'i' is greater than or equal to 10

    local i = 1

    repeat

      println("i: " i)

      i = i + 1

    until i >= 10



    ;; this will loop forever

    repeat

      println("Never gonna let you down")

    until false



    #+END_SRC



*** For Statement

    The first ~for~ statement representation closely resembles the for

    statement seen in C-based programming languages:



    #+BEGIN_SRC

    for  =   [step] do

      

    end

    #+END_SRC



    Examples



    #+BEGIN_SRC



    ;; loop from 0 to 10

    for i = 0 10 do

      println("i: " i)

    end



    ;; loop from first index to the length of the vector

    local x = [1 2 3]

    for i = 0 count(x) do

      println(i "-" x[i])

    end



    ;; provide a step

    for i = 0 10 2 do

      println("i: " i)

    end

    #+END_SRC



    The second type of ~for~ statement is called the ~for-each~

    statement. This is the more popular, and more often used loop

    conditional.



    #+BEGIN_SRC

    for  in  do

      

    end

    #+END_SRC



    Examples



    #+BEGIN_SRC



    ;; Print out each element of xs

    local xs = [1 2 3]

    for x in xs do

      println("Element: " x)

    end



    #+END_SRC

** Expressions

*** Arithmetic Operators

    - Addition :: ~+~

    - Subtraction :: ~-~

    - Multiplication :: ~*~

    - Division :: ~/~



    #+BEGIN_SRC



    println(2 + 2)

    println(2 + 2 - 2)

    println(2 * 2 - 5)

    println((2 + 2) * 4)

    println((2 / 2) * 5)



    #+END_SRC



*** Coercions & Conversions

    Arithmetic performed between integer values will remain as

    integers. It is only if you include a float within an arithmetic

    operation that it is automatically converted into a float value.



    Almost all types can be converted into a string using the ~str~

    function.



    #+BEGIN_SRC

    println(2 + 2) ;; 4 (integer)

    println(2 + 2.) ;; 4. (float)

    #+END_SRC



*** Relational Operators

    - Equality :: ~==~

    - Inequality :: ~!=~

    - Less Than :: ~<~

    - Greater Than :: ~>~

    - Less Or Equal Than :: ~<=~

    - Greater Or Equal Than :: ~>=~



    #+BEGIN_SRC

    println(2 == 2) ;; true

    println(2 != 1) ;; true

    

    local age = 12



    println(age < 18) ;; true

    println(age > 18) ;; false

    #+END_SRC



*** Logical Operators

    - And Operator :: ~and~

    - Or Operator :: ~or~



    #+BEGIN_SRC

    10 or 20 ;; 10

    nil or "a" ;; "a"

    nil and 10 ;; nil

    nil or 10 ;; 10

    10 and 20 ;; 20

    #+END_SRC

*** Length and Concatenation

    Unlike Lua, eden does not make use of special operators for length

    or concatenation. Instead, length can be obtained by using the

    function ~count~, and concatentation can be performed by using

    ~concat~.



    #+BEGIN_SRC

    count([1 2 3]) ;; 3

    count("test") ;; 4



    concat([1 2 3] [4 5 6]) ;; (1 2 3 4 5 6)

    #+END_SRC

*** Precedence

    Precendence is in this order (similar to lua):

    + ~or~, ~and~

    + ~<~, ~>~, ~<=~, ~>=~, ~!=~, ~==~

    + ~+~, ~-~

    + ~*~, ~/~

    + unary operators (~-~, ~not~)



    #+BEGIN_SRC

    println(2 + 2 * 4) ;; 10

    #+END_SRC

*** Collection Construction

    Constructing each of the main collections is straightforward

**** Vector

     - ~[1 2 3]~

     - ~vector(1 2 3)~

     - ~apply(vector list(1 2 3))~

     - to convert a collection to a vector, use ~vec~

**** Map

     - ~{:a 123 :b (2 + 2)}~

     - to convert a collection to a map, use ~into~

       #+BEGIN_SRC

       into({} [[:a 123] [:b "test"]])

       #+END_SRC

**** Set

     - ~#{:a :b :c}~

     - to convert a collection to a set, use ~set~

**** List

     - ~list(1 2 3)~

     - ~apply(list [1 2 3])~

     - to convert a collection to a list, use ~into~

       #+BEGIN_SRC

       into(list() vector(1 2 3 4))

       #+END_SRC

*** Function Calls

    Function calls are similar to lua:

    #+BEGIN_SRC

    ([arguments...])

    #+END_SRC



    Examples

    #+BEGIN_SRC

    x("test") ;; call the function in variable 'x' with the argument "test"

    #+END_SRC



*** Function Definitions

    Function creation can either be done standalone, or an anonymous

    function be assigned to a variable:



    #+BEGIN_SRC

    function add(x y)

      return x + y

    end



    add = function(x y)

      return x + y    

    end

    #+END_SRC



    In both cases, they can be assigned to a local variable



    #+BEGIN_SRC

    local function add(x y)

      return x + y

    end



    local add = function(x y)

      return x + y

    end

    #+END_SRC

** Module System



   *eden* has a simple module system. eden will look for files in

   order of increasing precedence:

   

   - If on linux, in /usr/share/eden/libs

   - If on linux, it will look in each of the colon separated paths in

     the Environment Variable ~EDEN_MODULE_PATH~

   - if on windows, it will look in each of the /semi-colon separated/

     paths in the Environment Variable ~EDEN_MODULE_PATH~

   - In your home folder, located at ~/.eden/libs (%HOME%/.eden/libs on windows)

   - The current working directory



   As an example, assuming I have a file named test.eden in the current

   working directory:



   #+BEGIN_SRC

   ;; test.eden



   local print-hello = function(name)

     println(str("Hello " name "!"))

   end



   export {:hello print-hello}



   #+END_SRC



   importing the module is simple:



   #+BEGIN_SRC

   ;; another_file.eden



   test = require "test"



   test.hello("Ben")



   #+END_SRC



   #+BEGIN_SRC sh

   $ eden another_file.eden

   Hello Ben!

   $ 

   #+END_SRC



** Standard Libraries

   Most of the standard libraries are handpicked community libraries

   that i've used in my other projects. The core libraries closely

   resemble the libraries seen in clojure

*** Core Library

    Most of the clojure core library has been implemented in Eden as a

    core library. The complete list of clojure.core can be found

    [[http://clojuredocs.org/clojure.core][here]]. Any dynamic variables, or macros have not been included from

    the core library.

*** ~system~ Library

    - ~system.env(s)~ :: Get the Environment Variable by the name ~s~

    - ~system.exit(n)~ :: Return from program with Exit Code ~n~

    - ~system.get-globals()~ :: Return all of the Eden program's global

         variables. Note that the keys are represented as symbols.

    - ~system.set-global(name value)~ :: Set global variable

         programmatically.

*** ~string~ Library

    The Eden string library is a direct mirror of the [[https://funcool.github.io/cuerdas/latest/][cuerdas]] string

    library. Please refer to the provided page for the list of

    functions, which can be accessed via the ~string~ variable.



    Examples

    #+BEGIN_SRC

    string.caseless=("Hello There!" "HELLO There!") ;; true

    string.human(:great-for-csv-headers) ;; "great for csv headers"

    #+END_SRC

*** ~filesystem~ Library

    The Eden filesystem library is a direct mirror of the [[https://github.com/Raynes/fs/][Raynes.fs]]

    filesystem library. The library api can be found [[https://raynes.github.io/fs/][here]].

*** ~io~ Library

    The Eden io library is a copy of the [[http://clojuredocs.org/clojure.java.io][clojure.java.io]] library.

*** ~$~, Specter Library

    For data transformations, the popular [[https://github.com/nathanmarz/specter][specter]] library has been

    included in the variable ~$~



    Examples

    #+BEGIN_SRC

    $.setval([:a $.END] [4 5] {:a [1 2 3]}) ;; {:a [1 2 3 4 5]}



    $.transform([$.filterer(odd?) $.LAST] inc range(1 9)) ;; (1 2 3 4 5 6 8 8)



    $.transform($.ALL inc #{1 2 3}) ;; #{2 3 4}

    #+END_SRC

*** Parsing Libraries

**** ~html~ Library

     - ~html.parse(s)~ :: Parses HTML string using [[https://github.com/davidsantiago/hickory][hickory]] (generates

                        hiccup style collection)

     - ~html.stringify(coll)~ :: Creates HTML string from collection

          using [[https://github.com/weavejester/hiccup][hiccup]]



     Also has css generator provided by [[https://github.com/noprompt/garden][garden]]

     + ~html.css.gen-css(coll)~ :: provided by garden.core/css

     + ~html.css.gen-style(coll)~ :: provided by garden.core/style

     + ~html.css.color~ :: several color functions from garden.color

     + ~html.css.units~ :: several unit functions from garden.units

**** ~json~ Library

     JSON library provided by [[https://github.com/dakrone/cheshire][cheshire]]

     - ~json.parse(s [opts])~ :: provided by cheshire.core/parse-string

     - ~json.stringify(coll [opts])~ :: provided by cheshire.core/generate-string

**** ~edn~ Library

     EDN library parser provided by [[https://github.com/clojure/tools.reader][tools.reader]]

     - ~edn.parse(s [opts])~ :: provided by clojure.tools.reader.edn/read-string

     - ~edn.stringify(coll [opts])~ :: clojure.core/pr-str

**** ~markdown~ Library

     Markdown library stringifier provided by [[https://github.com/yogthos/markdown-clj][markdown-clj]]

     - ~markdown.stringify(s) :: provided by markdown-clj.core/md-to-html-string

**** ~transit~ Library

     Transit Reader and Generator provided by [[https://github.com/cognitect/transit-clj][transit-clj]]



     - transit.parse(s)

     - transit.write(x)

*** ~http~ Library

    HTTP Server provided by [[http://www.http-kit.org/][http-kit]]

    HTTP Client provided by [[https://github.com/martinklepsch/clj-http-lite/][clj-http-lite]]

    HTTP Router provided by [[https://github.com/juxt/bidi][bidi]]

        



    - ~http.router.make-handler(coll)~ :: provided by bidi.ring/make-handler

    - ~http.server.run-server(handler [opts])~ :: provided by org.httpkit.server/run-server

    - ~http.client.get(url [opts])~ :: provided by clj-http.lite.client/get



    Example found at ./examples/eden/http_server.eden

    

*** ~shell~ Library

    Shell library provided by [[https://github.com/Raynes/conch][conch]], unfortunately it doesn't work due

    to reflection issues that will be resolved in future native

    executables



*** ~operator~ Library

    Includes all of the clojure equivalent operators. Useful for

    additional performance in certain applications

    * ~operator.add(x ...)~ :: clojure.core/+

    * ~operator.sub(x ...)~ :: clojure.core/-

    * ~operator.mult(x ...)~ :: clojure.core/*

    * ~operator.div(x ...)~ :: clojure.core//

    * ~operator.not(x)~ :: clojure.core/not

    * ~operator.and(x y)~ :: clojure.core/and, 2-arity wrapped macro

    * ~operator.or(x y)~ :: clojure.core/or, 2-arity wrapped macro

* Dark-corners of Eden



  Since *eden* uses EDN data values directly, it does mean some funky

  things can happen unexpectedly.



** Vectors get confused as indexes

   

   #+BEGIN_SRC



   map(inc [1 2 3])



   #+END_SRC

   

   This says /get the index [1 2 3] of inc/. The equivalent in clojure

   would be ~(get-in inc [1 2 3])~, which is not what we want. The

   solution is to use the ~vector~ function.

   

   #+BEGIN_SRC

   

   map(inc vector(1 2 3))



   #+END_SRC



   Note that indexing is only in effect after identifiers and function

   calls



   #+BEGIN_SRC

   x[1] ;; indexing

   list([1 2 3] x) ;; not indexing

   list([1 2 3] x [2]) ;; x[2] is an index!

   #+END_SRC



** The EDN parser gets confused with complex map hashes



   #+BEGIN_SRC



   local x = {

     :x 2 + 2

     :y 3 - 2

   }



   #+END_SRC



   The parser will fail, since the resulting map within eden appears

   as ~{:x 2, '+ 2, :y 3, '- 2}~. The solution is to group each

   expression in round brackets:



   #+BEGIN_SRC



   local x = {

     :x (2 + 2)

     :y (3 - 2)

   }



   ;; similarly for functions

   local y = {

     :hello (function(name) return str("Hello " name "!") end)

   }



   #+END_SRC



* Differences between Lua and Eden

** Array Indexing

   eden uses zero-indexing for array types, whereas lua uses

   one-indexing for array types.

   

   #+BEGIN_SRC lua

    -- Lua

    x = {"A", "B", "C"}

    print(x[1]) -- A

   #+END_SRC



   #+BEGIN_SRC clojure

    ;; eden

    x = ["A" "B" "C"]

    println(x[1]) ;; B

   #+END_SRC

** Equality Symbols

   Lua uses ~= to represent inequality, whereas Eden uses ~!=~



   #+BEGIN_SRC lua

   -- Lua

   print(true ~= false) -- true

   #+END_SRC



   #+BEGIN_SRC

   ;; eden

   println(true != false) ;; true

   #+END_SRC



** Module Systems

   *eden* adopts a module system with the special keyword ~export~ for

   exporting, whereas Lua reuses ~return~ to represent the module

   export.



   #+BEGIN_SRC lua

     -- Lua

     local x = {}

     x.test = function()

       print("test!")

     end



     return x

   #+END_SRC



   #+BEGIN_SRC clojure

     ;; eden

     local x = {}

     x.test = function()

       println("test!")

     end



     export x

   #+END_SRC



* Development

** Uberjar

   To generate a standalone uberjar file, run ~lein uberjar~

   

   The generated jar file will be located in ./target/eden--standalone.jar



** Native Executable Distribution

   Please read the Makefile for instructions on how to native compile

   *eden* using GraalVM.

*** Debian DPKG (Tested on Ubuntu 17.10)

    ~make dpkg~

*** Redhat RPM (Tested on Fedora 28)

    ~make rpm~

*** Tar Archive (Tested on Ubuntu 17.10)

    ~make tar~

** Testing

   Tests can be run with ~lein test~

* Features for Version 1.0.0 Stable Release



  - +Test Coverage for the entire standard language+

  - +Better parser errors (might require a parser rewrite)+

  - +support 'elseif clause in if conditionals+ (added in 0.4.0-SNAPSHOT)

  - +Additional standard libraries.+ (Several libraries have been

    added since 0.5.0-SNAPSHOT)

  - +clojure.string (or use funcool.cuerdas, can it native compile?)+

    (added in 0.3.0-SNAPSHOT)

  - +json parse and stringify libs (one that native compiles)+ (added in 0.3.0-SNAPSHOT)

* Future Unreachable(?) Goals

  - eden repl

  - clojurescript build with passing tests

  - metafunctions

  - lua table implementation

  - natively compiled database interface (sqlite, psql)