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Output Destinations#

Calva categorizes output into three types:

  • evaluation results: Clojure data returned from an evaluation.
  • evaluation output: stdout/stderr from an evaluation
  • other output: Other messages, logs, etc

With the setting calva.outputDestinations, you can configure where each category of output should go to:

  • the REPL Window
  • the Calva Says Output Channel
  • the Calva Output (pseudo) Terminal

The reason there are several options for this is partly legacy and partly because VS Code restricts the placement of different views in different ways. We hope you will find a combination of output destinations that suits you.

Commands for showing output destinations#

These are the commands and their default keyboard shortcuts for revealing output destinations

  • Calva: Show/Open the result output destination, without focusing it - ctrl+alt+o o
  • Calva: Show/Open the Calva says Output Channel, without focusing it - ctrl+alt+o c
  • Calva: Show/Open the Calva Output Terminal, without focusing it - ctrl+alt+o t
  • Calva: Show/Open REPL Window, also focuses it - ctrl+alt+o r

Focusing the output destination

The commands for opening the result destination all take a boolean argument for wether they should preserve focus or not. You can register keybindings that behave differently than the default ones. E.g.:

  "key": "ctrl+alt+o ctrl+alt+o",
  "command": "calva.showResultOutputDestination",
  "args": false
  "key": "ctrl+alt+o ctrl+alt+r",
  "command": "calva.showReplWindow", // Show/Open REPL Window
  "args": true

About stdout in the REPL Window#

Since Calva v2.0.423 the REPL Window prints stdout prepended with ; to make it into line comments. This is because stdout output easily breaks the Clojure structure of the REPL Window, making it misbehave in various ways. We made this change because as maintainers of Calva we have seen all too often how this hits users, and it is also taking too much of our Calva time to try mitigate the problem, which is fundamentally not fixable.

There are now other output destinations that do not have this limitation.

All that said. If you want to keep using the REPL Window for stdout output, and need the old behavior, you can enable the setting: calva.legacyPrintBareReplWindowOutput. Please note that at some point after we have created a dedicated Output Window, the REPL Window will probably be retired as a destination for output.

REPL process output (stdout and stderr)#

When Calva is connected to the REPL, the Output destination will by default print not only results of evaluations, but also:

  1. Things printed to stdout and stderr in the main thread of the evaluations
  2. Things printed to stdout and stderr from child threads of the evaluations
  3. Anything printed to stdout and stderr by the REPL process

You can control the default via the calva.redirectServerOutputToRepl setting. It defaults to true. Setting it to false before connecting the REPL will result in that 2. and 3. will not get printed in the Output destination. It will then instead be printed wherever the REPL process is printing its messages, usually the terminal from where it was started (the Jack-in terminal if Calva started the REPL).

See also#