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Orchard

A Clojure library designed to provide common functionality for Clojure development tools (e.g. Clojure editor plugins and IDEs).

Right now orchard provides functionality like:

  • enhanced apropos
  • classpath utils (alternative for java.classpath)
  • value inspector
  • Java class handling utilities
  • Utilities for dealing with metadata
  • Namespace utilities
  • Fetching ClojureDocs documentation
  • Finding function dependencies (other functions invoked by a function) and usages

Why?

Much of the tooling code required to build Clojure editors and smart REPLs is tool-agnostic and should be reused between tools, instead of copied and altered in each and every tool.

Having a common tooling foundation typically means:

  • Better foundation (e.g. more functionality, good documentation, etc) with more contributors
  • Less work for tool authors as they don't have to reinvent the wheel for every tool
  • Happier end users

Design

Orchard is meant to be used to build programmer tooling relying on inspecting the state of a running REPL. REPL-powered tooling has been a core Lisp idea for many years and there are many Clojure libraries in that space (e.g. compliment, tools.trace, sayid, etc).

One thing to keep in mind is that Orchard relies (mostly) on runtime information, not the source code itself. In simple terms - only code that's loaded (evaluated) will be taken under consideration. That's pretty different from the static analysis approach taken by tools for most programming languages where it's not possible to easily inspect the state of running program.

Some other design goals are listed bellow.

No Runtime Dependencies

Orchard is meant to run alongside your application and we can't have a dev tools library interfere with your app right? Dependency collisions are nasty problems which are best solved by making sure there can't be any shared libraries to cause the conflict.

Currently Orchard has one runtime dependency (dynapath), but we hope to eliminate it at some point.

API Optimized for Editors

Code editors can't know what symbols resolve to without consulting a REPL that's why they would typically send a combination of a symbol name and some ns (e.g. the current namespace), so they can be resolved to some var on which an operation would be invoked.

That's why the majority of the functions in Orchard take a combination of a ns and a symbol instead of a var. Probably down the road we'll provide var-friendly versions of most functions as well.

REPL Agnostic

No matter whether you're using nREPL, a socket REPL, unrepl or prepl, Orchard has your back. nREPL clients might opt to wrap some of the Orchard functionality in middleware for convenience (as cider-nrepl does), but they can just eval away if they please.

API Documentation

Documentation for the master branch as well as tagged releases are available here.

Usage

orchard requires Clojure 1.8+ and Java 8+.

Just add orchard as a dependency and start hacking.

[cider/orchard "0.7.1"]

Consult the API documentation to get a better idea about the functionality that's provided.

Configuration options

So far, Orchard follows these options, which can be specified as Java system properties (which means that end users can choose to set them globally without fiddling with tooling internals):

  • "-Dorchard.use-dynapath=false" (default: true)
    • if false, all features that currently depend on dynapath (and therefore alter the classpath) will be disabled.
    • This is a way to avoid a number of known issues: #103, #105, #112.
    • Note that if this option is false, Orchard clients will have to figure out themselves a way to e.g. fetch Java sources.
      • It is foreseen that soon enough this will be reliably offered as a Lein plugin.
  • "-Dorchard.initialize-cache.silent=true" (default: true)
    • if false, the class info cache initialization may print warnings (possibly spurious ones).xx

History

Originally SLIME was the most popular way to program in Clojure with Emacs and a lot of useful functionality was created for it to support things like code completion, value inspection, finding references, apropos and so on. This functionality was implemented as a swank adapter written in Clojure and lived in the swank-clojure project.

Subsequently CIDER and cider-nrepl replaced SLIME and swank, and much code was moved from swank-clojure to cider-nrepl and continued to evolve there.

You can watch the presentation The Evolution of the Emacs tooling for Clojure to learn more about all of this.

This project is an effort to prevent repeating the mistakes of the past - cider-nrepl was split into two libraries, so that non-nREPL clients can make of use of the general functionality contained in cider-nrepl (e.g. things like apropos, inspect, etc).

License

Copyright © 2018-2021 Bozhidar Batsov & contributors

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.