NAME

    Lingy - A Perl implementation of Clojure

SYNOPSIS

    Run the Lingy REPL:

        $ lingy
        Lingy 0.1.7 [perl]
    
        user=> (p<TAB>
        pos?     println  prn      pr-str
        user=> (prn "Hello, world!")
        "Hello, world!"
        nil
        user=>

    or a Lingy one-liner:

        $ lingy -e '(println "Hello, world!")'
        Hello, world!

    or run a Lingy program file:

        $ echo '(println "Hello, world!")' > hello.ly
        $ lingy hello.ly
        Hello, world!

    or run an example Lingy program:

        $ wget -q https://raw.githubusercontent.com/ingydotnet/lingy/main/eg/99-bottles.ly
    
        $ cat 99-bottles.ly
        (defn main [number]
          (let [
            paragraphs (map paragraph (range number 0 -1)) ]
            (map println paragraphs)))
    
        (defn paragraph [num]
          (str
            (bottles num) " of beer on the wall,\n"
            (bottles num) " of beer.\n"
            "Take one down, pass it around.\n"
            (bottles (dec num)) " of beer on the wall.\n"))
    
        (defn bottles [n]
          (cond
            (= n 0) "No more bottles"
            (= n 1) "1 bottle"
            :else (str n " bottles")))
    
        (main (nth *ARGV* 0 99))
    
        $ lingy 99-bottles.ly 3
        3 bottles of beer on the wall,
        3 bottles of beer.
        Take one down, pass it around.
        2 bottles of beer on the wall.
    
        2 bottles of beer on the wall,
        2 bottles of beer.
        Take one down, pass it around.
        1 bottle of beer on the wall.
    
        1 bottle of beer on the wall,
        1 bottle of beer.
        Take one down, pass it around.
        No more bottles of beer on the wall.

STATUS

    Lingy is in ALPHA status.

DESCRIPTION

    Lingy is an implementation of the Clojure language that is written in
    Perl and hosted by Perl. Programs and modules written in Lingy have
    full access to Perl and its CPAN modules.

    Perl modules can be written in Lingy and distributed on CPAN. (In the
    future) Lingy code is compiled to a bytecode and should perform on the
    same order of magnitude as XS modules.

    Since Lingy will be a complete Clojure implementation, it should be
    able to run programs written in Clojure and make use of libraries
    written in Clojure.

    Clojure is a language that cleanly solves many of the problems of Java
    including making concurrency simple, and writing functional programs
    with mostly immutable data types. It is a Lisp dialect that is hosted
    by Java and compiles to JVM byte code. It has access to any libraries
    that target the JVM.

    Much of the Clojure language is written in Clojure (self hosted) and
    Lingy actually uses the Clojure source code. A variant of Clojure
    called ClojureScript uses the same Clojure source code but is hosted by
    JavaScript with full access to NPM modules. Lingy also intends to
    eventually be ported to and hosted by many other programming languages.

    Lingy started as a Perl implementation
    <https://github.com/ingydotnet/mal/tree/perl.2/impls/perl.2> of the
    Make a Lisp <https://github.com/kanaka/mal> project. This provided a
    bare-bones Clojure-inspired Lisp interpreter from which Lingy has grown
    upon.

INSTALLATION

        cpanm Lingy

LINGY CLI USAGE

    The Lingy language installs a command lingy. You can use this command
    to run Lingy programs, start a Lingy REPL or run Lingy one-liner
    expressions.

      * lingy --repl (or just lingy)

      Starts a Lingy interactive REPL. The REPL has readline support that
      includes:

	* Command history

	* CTL-R searching

	* Parentheses match highlighting

	* CTL-C to abort a command w/o leaving REPL

      Use CTL-D to exit the REPL

      * lingy program.ly foo bar

      Run a Lingy program passing in arguments. Arguments are available in
      Lingy as *ARGV*.

      * cat program.ly | lingy - foo bar

      Run a Lingy program from STDIN and pass in arguments. The - means run
      from STDIN instead of a file. If there are no arguments you can omit
      the -.

      * lingy -e '(println "Hello" (nth *ARGV* 0))' world

      Run a Lingy one-liner with arguments.

      When used with --repl, run the -e code first, then enter the REPL.

 LINGY CLI OPTIONS

      * -e <string>, --eval=<string>

      A Lingy string to evaluate.

      * -r, --repl

      Start a Lingy REPL. Can be used with -e.

      * --ppp

      Print the Lingy compiled AST for a -e expression.

      * --xxx

      YAML dump the Lingy compiled AST for a -e expression.

LINGY REPL USAGE

    If you run lingy --repl (or just lingy) you will start a Lingy
    interactive REPL. You can run Lingy commands and see the output.

    The REPL has command line history to save all your commands. It also
    has readline history search (ctl-r) and tab completion.

 USING THE CLOJURE REPL IN THE LINGY REPL

    If you have Clojure installed on your system and you run this command
    in the Lingy REPL: (clojure-repl-on), then every command you enter will
    be evaluated both by Lingy and Clojure. Run (clojure-repl-off) to turn
    it off. Start the Lingy REPL with lingy --clj to turn it on from the
    start.

    Also if you run a command like ;;;(source first) it will only run on
    Clojure. The command is a comment to Lingy but the REPL will remove the
    ;;; and pass it to Clojure.

    Using this feature is a great way to compare how Lingy and Clojure
    work. Eventually they should be very close to identical but currently
    Lingy is still a baby.

SEE ALSO

      * Clojure <https://clojure.org/>

      * YAMLScript <https://metacpan.org/pod/YAMLScript>

      * Test::More::YAMLScript
      <https://metacpan.org/pod/Test::More::YAMLScript>

AUTHORS

      * Ingy döt Net ingy@ingy.net <mailto:ingy@ingy.net>

COPYRIGHT AND LICENSE

    Copyright 2023 by Ingy döt Net

    This is free software, licensed under:

    The MIT (X11) License

