candeira/flk

A LISP that runs wherever Bash is

Fleck is a Clojure-like LISP that runs wherever Bash is.

Get it

curl -s https://chr15m.github.io/flk/flk > flk && chmod 755 flk
./flk

Examples | Reference | FAQ | make-a-lisp

What?

$ echo '(println "Hello world!") (println "Hostname:" (sh* "hostname")))' > example.clj
$ ./flk example.clj
Hello world!
Hostname: diziet

Why?

Now you can use a humble LISP to do Bash things. Bash as a scripting language has many edges, but it is everywhere. Fleck attempts to round off the edges.

Fleck runs on Bash 4 and higher.

How?

Almost all of this code is from the make-a-LISP project. All I've done is put together a simple Makefile to package it up into an easily deployable single-file bash script.

Reference

A list of macros and functions that are present in Fleck.

Built-ins

This is the set of built-ins from the make-a-lisp project. These more or less work but are generally more limited in functionality than their Clojure equivalents. For example the addition function (+) can only add two integers at a time.

def! | defmacro! | if | do | fn* | try* | sh* | let* | quote | quasiquote | macroexpand | type | = | throw | nil? | true? | false? | string? | symbol | symbol? | keyword | keyword? | number? | fn? | macro? | pr-str | str | prn | println | readline | read-string | slurp | < | <= | > | >= | + | - | * | / | time-ms | list | list? | vector | vector? | hash-map | map? | assoc | dissoc | get | contains? | keys | vals | sequential? | cons | concat | nth | first | rest | empty? | count | apply | map | conj | seq | with-meta | meta | atom | atom? | deref | reset! | swap!

Aliases

These are wrappers around the limited make-a-lisp versions and are much more limited than the Clojure equivalents.

let | when | def | fn | defn

Mal extras

These functions are pulled from a selection of mal/lib/*.mal.

partial | inc | dec | zero | identity

Fleck extras

These functions are hand crafted Fleck specials design to make common shell scripting tasks easier.

• (str-replace STRING FIND REPLACE) - Replace all occurrences of the string FIND in STRING with the string REPLACE.
• (str-split STRING SPLIT-CHARACTER) - Split STRING into a list of strings on the single characters SPLIT-CHARACTER.
• (dc OPERATOR ARRAY-OF-NUMBERS) - Wraps the dc command to do decimal math. E.g. (dc '+ [1 2 3]) yeilds 6.

Compile

You can make a pure bash script from your Fleck script by bundling your script and Fleck together into a new script.

Say you have a Fleck script called wow.clj, you can bundle it as follows:

make DEST=wow INSERT=./wow.clj NOREPL=1

This will produce a new standalone script called wow with Fleck + wow.clj bundled together.

When you run wow the embedded wow.clj will be run by the embedded Fleck.

FAQ

Think of this as homoiconic Bash rather than Clojure, and code as if you're in Bash.

Will my favourite piece of Clojure run in this?

No, it's bash.

Some subset of Clojure-like code will run. See the documentation and examples.

Why can't I add more than 2 numbers together?

It's bash. Try the dc function: (dc '+ [1 2 3 4])

Where are the floating point numbers?

It's bash. Try the dc function for decimals: (dc '* [8.2 3.5])

Why can't I iterate on a string?

Try (seq "somestring").

How do I do destructuring?

You can't.

Why is it called Fleck?

At 36k and running on any machine with Bash 4, the name seemed appropriate.

 fleck

    n. A tiny mark or spot.
    n. A small bit or flake.