babashka.cli

Turn Clojure functions into CLIs with minimal effort.

Quick Start

(require '[babashka.cli :as cli])

;; Parse basic options
(cli/parse-opts ["--port" "8080"] {:coerce {:port :long}})
;;=> {:port 8080}

;; Parse with subcommands
(cli/parse-args ["deploy" "prod" "--force"]
  {:coerce {:force :boolean}})
;;=> {:cmds ["deploy" "prod"] :opts {:force true}}

Key Features

Flexible Syntax: Both :opt and --opt styles supported
Type Coercion: Automatic or explicit type conversion
Subcommands: Built-in dispatch mechanism
Validation: Required options, restrictions, custom validators
Collections: Handle repeated options naturally
Help Generation: Format specs into help text

Basic Coercion

(cli/parse-opts ["--port" "8080" "--verbose"]
  {:coerce {:port :long :verbose :boolean}})
;;=> {:port 8080 :verbose true}

Aliases

(cli/parse-opts ["-p" "8080" "-v"]
  {:alias {:p :port :v :verbose}
   :coerce {:port :long :verbose :boolean}})
;;=> {:port 8080 :verbose true}

Positional Arguments

(cli/parse-opts ["deploy" "production"]
  {:args->opts [:action :env]})
;;=> {:action "deploy" :env "production"}

Validation

(cli/parse-args ["--port" "8080"]
  {:coerce {:port :long}
   :require [:port :host]
   :validate {:port pos?}})
;; Throws if :host missing or :port not positive

Subcommand Dispatch

(defn deploy [opts]
  (println "Deploying to" (get-in opts [:opts :env])))

(cli/dispatch
  [{:cmds ["deploy"] :fn deploy}]
  ["deploy" "--env" "prod"])

Using the Skill

Invoke with:

claude-code --skill clojure-libraries:babashka.cli

The skill provides comprehensive documentation including:

Complete API reference for all functions
Coercion types and collection handling
Validation and error handling patterns
Subcommand routing and dispatch
Help text generation
Common CLI patterns and recipes

Learning Path

Start with parse-opts for simple option parsing
Use parse-args when you need positional arguments
Add validation with :require, :restrict, :validate
Implement subcommands with dispatch
Generate help text with format-opts

Resources

Repository: https://github.com/babashka/cli
Documentation: https://cljdoc.org/d/org.babashka/cli
Blog Post: https://blog.michielborkent.nl/babashka-cli.html
Babashka Book: https://book.babashka.org/

Installation

;; deps.edn
{:deps {org.babashka/cli {:mvn/version "0.8.60"}}}

;; bb.edn (built-in since babashka 0.9.160)
{:deps {org.babashka/cli {:mvn/version "0.8.60"}}}