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. Not all Clojure core functions are supported yet, but can be easily added. PRs welcome.

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 --raw flag is provided. When using the --println flag, the output is printed using println instead of prn.

The current version can be printed with:

bb --version
0.0.3

Examples:

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

$ ls | bb --raw '(count *in*)'
11

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

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

Functions are written using the reader tag #f. Currently up to three arguments are supported.

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

Regexes are written using the reader tag #r.

$ ls | bb --raw '(filterv #f(re-find #r "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 --raw '(shuffle *in*)' | bb --println '(str/join "\n" *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 --raw '(map-indexed #f[%1 %2] *in*))' | \
bb '(keep #f(when (re-find #r"(?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

License

Copyright © 2019 Michiel Borkent

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