edadma / funl

a functional dynamically typed scripting language


The FunL Programming Language

FunL (pronounced "funnel") is a functional dynamically typed scripting language. The name FunL stands for "fun language", but it can also stand for "functional language". One of the goals in creating FunL was to make a scripting language that would be as enjoyable and convenient to use as Python but with the added support for pattern matching and more of a "functional" style of programming. FunL has the same kind of indentation or "off-side rule" syntax as Python.

As an example, here is a tail-recursive version of the well known factorial function.

def factorial( n )
  | n >= 0 =
      fact( acc, 0 ) = acc
      fact( acc, n ) = fact( acc*n, n - 1 )

    fact( 1, n )
  | otherwise = error( "factorial: n should be non-negative" )

Here is the same calculation expressed more concisely (which is also tail-recursive internally).

def factorial( n ) = product( 1..n )

Another goal in creating FunL was to have a scripting language that is highly Java and Scala interoperable. FunL is implemented in Scala and therefore relies upon both the Java and Scala runtime support libraries.

To give a small example of a complete program in FunL that does something useful, here is a simple static file web server (in under 50 lines).

native java.io.{File, InputStreamReader, BufferedReader, PrintStream}
native java.net.ServerSocket
import concurrent.thread
import io.readFile

val listener = ServerSocket( port )
val dir = File( '.' ).getCanonicalPath()
val types = {'txt': 'text/plain', 'html': 'text/html', 'css': 'text/css',
  'js': 'application/javascript', 'png': 'image/png', 'gif': 'image/gif', 'jpeg': 'image/jpeg'}

def connection( socket ) =
  input = BufferedReader( InputStreamReader(socket.getInputStream(), 'UTF-8') )
  output = PrintStream( socket.getOutputStream(), true )

  def response( code, type ) =
    output.println( 'HTTP/1.1 ' + code )
    output.println( 'Content-Type: ' + (if type != null then type else 'text/html') )
    if (type == null) then output.println( '<!DOCTYPE html><html><header><title>' + code + '</title><body><h1>' + code + '</h1></body></html>' )

  val line = input.readLine()

  if line != null
    val (request, url, _) = tuple( line.split(' +') )
    val file = File( dir + url + (if url == '/' then 'index.html' else '') ).getCanonicalFile()

    if request == 'GET'
      if file.getPath().startsWith( dir ) and file.exists() and file.isFile() and file.canRead()
        ext = list( file.getPath().split('\\.') ).last()
        if (ext in types)
          response( '200 OK', types(ext) )
          output.write( readFile(file) )
          response( '415 Unsupported Media Type', null )
        response( '404 Not Found', null )
      response( '405 Method Not Allowed', null )


loop thread( connection, listener.accept() ).start()


FunL is distributed under the MIT License, meaning that you are free to use it in your free or proprietary software.


The project's website is http://edadma.github.io/funl-docs/ where you will find documentation and download instructions so that you can get a binary executable of the interpreter.

There are also many examples of FunL code to be found at http://rosettacode.org/wiki/FunL, which serve to document how FunL can be used in solving various types of programming problems in a concise and functional way.


Use the following elements to use FunL in your Maven project:



Add the following to your build.sbt file to use FunL in your SBT project:

resolvers += "Hyperreal Repository" at "https://dl.bintray.com/edadma/maven"

libraryDependencies += "ca.hyperreal" %% "funl" % "0.20"



  • SBT 13.2+
  • Java 6+

Clone and build:

git clone git://github.com/edadma/funl.git
cd funl
sbt assembly

This will build an executable requiring only that Java be installed. You can now also type

sbt run

to start the REPL, or

sbt "run <FunL script file>"

to execute a script. Note that the double quotes are required.


These instructions apply to Ubuntu or any Debian based distribution. It is assumed that Java is installed and in your PATH, as well as the unzip utility.

In these instructions <path to jar> means the path where the executable JAR file was downloaded to, and <path to funl> means the path to the directory that you created in which to install FunL.

Here are the steps.

  1. Download the latest release from https://dl.bintray.com/edadma/generic/funl-0.20.jar.
  2. Create a directory where FunL should be installed.
  3. Start a shell.
  4. Enter cd <path to jar>
  5. Enter unzip funl-0.20.jar bin/funl -d <path to funl>
  6. Enter chmod a+x <path to funl>/bin/*
  7. Enter cp funl-0.20.jar <path to funl>/bin
  8. Open ~/.profile in an editor.
  9. Add PATH="<path to funl>/bin:$PATH"
  10. Enter source ~/.profile
  11. Enter funl

After the last step, you should see

    ______            __
   / ____/_  __ ___  / /     FunL Programming Language
  / __/ / / / / __ \/ /      (c) 2014 Edward A. Maxedon, Sr.
 / /   / /_/ / / / / /__     http://funl-lang.org/
/_/    \____/_/ /_/____/                                     

Welcome to FunL version 0.20
Type in expressions to have them evaluated.
Type :help for more information.

indicating that the installation worked. You are inside the FunL REPL. Press Ctrl-C to get out.


The latest development executable can be downloaded from https://dl.bintray.com/edadma/generic/funl-0.20.jar.