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*debug* (keyword)

*debug* is bound to the keyword :debug—it provides a global alias to the dynamic binding indicating whether the integrated debugger is enabled.

• Official Docs
• JanetDocs

repl> (root-env '*debug*)
@{:doc "Enables a built in debugger on errors and other useful features for debugging in a repl."
  :dyn true
  :source-map ("boot.janet" 1338 1)
  :value :debug}

Things I Learned

• Janet has an integrated debugger!
• Starting janet with the -d, --debug flag enables the debugger. Usually Janet exits on error when executing a file, but the -p, --persistent flag can be used to enter the debugger on error.
• When the :debug dynamic binding is truthy, you can enter the debugger by raising an error, reaching a breakpoint (ref: debug/break), calling debug, or calling debugger with a given fiber (and maybe other ways).

Created: Thursday October 16, 2025 @ 12:47:39 AM EDT