Planck Namespaces

In order to make Planck more useful for doing actual work and interacting with your computer and the outside world, some native I/O facilities have been added to the JavaScriptCore instance running in Planck and these have been exposed via a few namespaces. To make things easier to use, the functions in these namespaces adhere fairly closely to existing Clojure / ClojureScript analogs.

The code for these namespaces is included directly in the Planck binary, so they are always available—you just need to require them.

These namespaces comprise

To explore these namespaces, you can evaluate (dir planck.core), for example, to see the symbols in planck.core, and then use the doc macro to see the docs for any of the symbols.


This namespace includes basic I/O capabilities like slurp, spit and read-line. The I/O facilities are expressed in protocols defined in planck.core modeled after those in Clojure, like IReader, IOutputStream, etc., and these capabilities cooperate with facilities defined in

Planck core also hosts some dynamic vars of interest like *in* and *out*.

The planck.core/file-seq function imitates clojure.core/file-seq.

If you need to prompt for a password, take a look at planck.core/read-password.

The planck.core namespace defines dynamic functions like resolve, ns-resolve, and intern.

Additionally, planck.core/exit is a function that takes an integer exit-value argument, so you can cause a Planck script to exit with any desired Unix exit value.


This namespace includes a few macros that are useful when working at the REPL, such as doc, dir, source, etc.

This namespace defines a lot of the IOFactory machinery, imitating

Additionally, filesystem facilities like file, delete-file, and file-attributes are available.

This namespace imitates, and defining the sh function and with-sh-dir / with-sh-env macros that can be used to execute external command-line functions.

With this escape hatch, you can do nearly anything: Move files to remote hosts using scp, etc.


This namespace provides facilities for interacting with HTTP servers. For example:

(planck.http/get "")

will fetch the main page of the Planck website, returning the status code, headers, and body in a map structure.


This namespace provided access to environment variables, modeled after Environ. For example

(:home planck.environ/env)

will access the HOME environment variable.