babashka

A pure, fast and (severely!) limited version of Clojure in Clojure for shell scripting.

Properties:

• pure (no side effects)
• fast startup time
• interprets only one form
• reads from stdin and writes to stdout

Rationale

Most of your script is in bash, but you want a tiny sprinkle of Clojure.

If most of your shell script evolves into Clojure, you might want to turn to:

• planck
• joker
• closh
• lumo

Status

Experimental. Breaking changes are expected to happen at this phase.

Installation

Linux and macOS binaries are provided via brew.

Install:

brew install borkdude/brew/babashka

Upgrade:

brew upgrade babashka

You may also download a binary from Github.

Usage

... | bb [--raw] [--println] '<Clojure form>'

There is one special variable, *in*, which is the input read from stdin. The input is read as EDN by default, unless the -i flag is provided, then the input is read as a string split by newlines into a vector.. The output is printed as EDN by default, unless the -o flag is provided, then the output is printed using println. To combine -i and -o you can use -io.

The current version can be printed with bb --version.

Currently only the macros if, when, and, or, -> and ->> are supported.

Examples:

$ ls | bb -i '*in*'
["LICENSE" "README.md" "bb" "doc" "pom.xml" "project.clj" "reflection.json" "resources" "script" "src" "target" "test"]

$ ls | bb -i '(count *in*)'
12

$ bb '(vec (dedupe *in*))' <<< '[1 1 1 1 2]'
[1 2]

$ bb '(filterv :foo *in*)' <<< '[{:foo 1} {:bar 2}]'
[{:foo 1}]

Anonymous functions literals are allowed with currently up to three positional arguments.

$ bb '(#(+ %1 %2 %3) 1 2 *in*)' <<< 3
6

$ ls | bb -i '(filterv #(re-find #"reflection" %) *in*)'
["reflection.json"]

Shuffle the lines of a file:

$ cat /tmp/test.txt
1 Hello
2 Clojure
3 Babashka
4 Goodbye

$ < /tmp/test.txt bb -io '(shuffle *in*)'
3 Babashka
2 Clojure
4 Goodbye
1 Hello

Find the line numbers where the word Clojure occurs using a case insensitive regex:

$ cat /tmp/test.txt
foo
Clojure is nice
bar
when you're nice to clojure

$ < /tmp/test.txt bb -i '(map-indexed #(vector %1 %2) *in*))' | \
bb '(keep #f(when (re-find #"(?i)clojure" (second %)) (first %)) *in*)'
(1 3)

Test

Test on the JVM:

script/test

Although this tool doesn't offer any benefit when running on the JVM, it is convenient for development.

Test the native version:

BABASHKA_TEST_ENV=native script/test

Build

You will need leiningen and GraalVM.

script/compile

Gallery

Here's a gallery of more useful examples. Do you have a useful example? PR welcome!

Fetch latest Github release tag

For converting JSON to EDN, see jet.

$ curl -s https://api.github.com/repos/borkdude/clj-kondo/tags \
| jet --from json --keywordize --to edn \
| bb '(-> *in* first :name (subs 1))'
"2019.07.31-alpha"

License

Copyright © 2019 Michiel Borkent

Distributed under the EPL License, same as Clojure. See LICENSE.