nreplops-tool (nr)

nreplops-tool (nr) is a non-interactive nREPL client designed to be used in shell scripts and on the command-line.

Early α warning: This project at a very early development phase. While the tool is probably reasonably usable (and the author uses it daily) the current development focus is not on quality, stability, or documentation.

Try it out in 1 minute

This example assumes you are able to install packages with Homebrew. See the Installation section below for other options.

Start by installing nreplops-tool (nr) and Babashka (bb):

brew install mjhanninen/sour/nreplops-tool borkdude/brew/babashka

Launch a Babashka nREPL server (that listens on the port 1667 by default):

bb nrepl-server

Open another terminal and evaluate an expression with nr:

nr -p 1667 -e '(println "Hello, world!")'

Quick examples

Before starting make sure that you have a Clojure nREPL server running in the background and there is a corresponding .nrepl-port file in either the current working directory or any of its ancestor.

Evaluate the expression (+ 1 2) on a nREPL server:

$ nr -e '(+ 1 2)'
3

Pass the expressions through a pipe:

$ echo '(+ 1 2)' | nr
3

Evaluate the content of a file:

$ echo '(+ 1 2)' > plus.clj
$ nr plus.clj
3

Create an executable nREPL scripts:

$ cat <<EOF > plus.nrepl
+ #!/usr/bin/env nr -!
+ (+ 1 2)
+ EOF
$ chmod +x plus.nrepl
$ ./plus.nrepl
3

Suppose the nREPL server had a function called get-user-by-email that searched in retrieved users from the application database by email. A script exposing that functionality to the command line could look something like this:

$ cat <<EOF > get-user-by-email.nrepl
+ #!/usr/bin/env nr -! --no-results
+ (clojure.pprint/pprint
+   (get-user-by-email db "#nr[1]"))
$ EOF
$ chmod +x get-user-by-email.nrepl
$ ./get-user-by-email.nrepl wile.e.coyote@example.com
{:name "Wile E. Coyote"
 :email "wile.e.coyote@example.com"
 :phone "555-555 555"}

Installation

Homebrew

brew install mjhanninen/sour/nreplops-tool

Cargo

cargo install nreplops-tool

Building from sources

git clone https://github.com/mjhanninen/nreplops-tool.git
cargo install --path .

Goals

• Easy of use in shell scripts
• Consistency and interoperability with Babashka and jq

License

Copyright 2022 Matti Hänninen

Licensed under the Apache License 2.0

Please see the LICENSE and NOTICE files.