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The Juno.jl Front-End

Juno provides some functionality using Atom's UI, which will usually have a fallback for use in other environments.

The isactive() function will provide an interface for figuring out whether the current session is running within Juno:


Enhanced Display

Juno.jl includes features which allow package developers to create enhanced displays in Juno.

For example, we can print provide structured display for arbitrary objects (similar to Base.dump)




Profiles collected by Profile.@profile can be displayed as a flame chart (similar to ProfileView.jl) inside of Juno by calling Juno.profiler. There's also a Juno.@profiler macro which does the same as Profile.@profile but also displays the collected information as a flame chart after clearing all the collected backtraces beforehand. Just using the Juno.@profiler macro will be enough for most cases, and it's way much simpler.


profiler view

Clicking on one of the boxes in the profile view will take you to the corresponding file/line. The width of the boxes in the profile view and the length of the lines in the editor correspond to the percentage of calls made in that line. Also note that there are specially colored lines:

  • yellow means the line was dynamically dispatched
  • red means there was a garbage collection happened at the line

!!! tip See the performance tips or this thread for how/why dynamic dispatch can affect the performance.

To clear the profile view and the in-editor display, click the Forget Plot button in the profile view toolbar or use Julia Client: Clear Profile command.

Progress Meters

Juno.jl allows package developers to use the progress bar which is provided in the Atom window. For example, you can easily show a progress meter for a for loop or a comprehension via the command:

@progress for ...


The following functions provide this interface:


It is recommended to either use the @progress macro or the

progress(name = "Foo") do p


notation to ensure that the progress bars are properly unregistered in the frontend.


Juno.jl lets package developers interact with users via the Atom frontend.


allows the user to select from a list of options:




sends an OS-level notification:



sends an notification via Atom's builtin notification API:



queries the currently used syntax colors in Atom (, which can be used to generate a plot theme or an OhMyREPL syntax theme from that, etc).


!!! note "example usecases" - plot theme: Plots.theme(:juno) automatically create a plot theme based on your Atom syntax color, using this function internally - OhMyREPL.jl theme: the package doesn't not provide an integrated theme by default, but here are snippets you can create its theme based on your Atom syntax theme: + +


clears the Juno REPL:


!!! note you can clear any Juno terminal via Ctrl-J Ctrl-C (i.e. Julia Client: Clear REPL command).

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