logo Reveal: Read Eval Visualize Loop for Clojure


Clojars Project Slack Channel


Repl is a great window into a running program, but the textual nature of its output limits developer's ability to inspect the program: a text is not an object, and we are dealing with objects in the VM.

Reveal aims to solve this problem by creating an in-process repl output pane that makes inspecting values as easy as selecting an interesting datum. It recognizes the value of text as a universal interface, that's why its output looks like a text: you can select it, copy it, save it into a file. Unlike text, reveal output holds references to printed values, making inspecting selected value a matter of opening a context menu.

Unlike datafy/nav based tools, Reveal does not enforce a particular data representation for any given object, making it an open set — that includes datafy/nav as one of the available options. It does not use datafy/nav by default because in the absence of inter-process communication to datafy is to lose.

Not being limited to text, Reveal uses judicious syntax highlighting to aid in differentiating various objects: text java.lang.Integer looks differently depending on whether it was produced from a symbol or a class.


You can find overview, setup instructions and more at vlaaad.github.io/reveal.

Versioning, stability, public and internal code

Reveal uses 1.MAJOR.REVISION versioning where: - 1 is a static prefix for compatibility with semantic versioning. Reveal should never introduce breaking changes, so if an update broke something, please file a bug report; - MAJOR is a number that is incremented when there are significant changes or improvements to Reveal; - REVISION is a commit number from the beginning of a history.

Reveal's compatibility promise applies to its public API: vlaaad.reveal and vlaaad.reveal.ext namespaces, everything else is implementation detail that is subject to change. Reveal's UI and controls might change in the future.

To do

  • structural navigation
  • text search:
  • should be reversible: escape scrolls to the place of search start if there is a highlight
  • could show number of matches and index of current match
  • contextual eval:
  • alt+up/down for history (persist history? per what?)
  • auto-insert closing brackets
  • pick some useful ns to eval in
  • fork out/err in repl/nrepl:
  • for full experience we should fork System/out and System/err, and re-bind roots of *out* and *err* — is it a good idea?
  • option to dispose javafx on quitting the repl - useful for entry points
  • multiple accordions
  • more actions:
  • view files ending with .html as web pages
  • remember window position and size
  • popup might appear in weird locations
  • very long lines have poor performance
  • bigger font size may break result header scrolling

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