This is a study note on how to develop Clojure using VS code. It is based on the Calva Usesr Guide.

1 Installation

There are two competing VS code extensions: Calva and Andrey Lisin’s clojureVSCode. Calva is the better one in terms of recency, commits and collaborators.

Calva is a REPL powered Clojure and Clojure Script development tool that supports inline code evaluation, Paredit, code formatting, a test runner, syntax highlighting, linting, and more.

2 Jack-in

To provide many of its IDE features, Calva relies on nREPL middleware, mainly cider-nrepl and, for ClojureScript, piggieback. Jack in creates the command that starts Calva with these dependencies satisfied. The details are explained in Learn about Jack-in.

Jack-in supports Leiningen and Clojure CLI for Clojure. It supports Figwheel Main, shadow-cljs and Nashorn for ClojureScript.

Open a project root folder in VS Code, then ctrl+alt+c ctrl+alt+j to open start Jack in, then specify project type and profile to start.

Calva only supports one project at a time per VS Code window. For a full stack project, create two workspaces and use them in two windows.

See Custom Connect Sequences for customizing Jack-in.

3 Code Evaluation

Calva has the notions of the current form and the current top level form. When you place the cursor to any code, it highlights the current form. The current top level form refers the various defs such as defn, defthis and defthat. The (comment ...) creates a new context for top level forms.

  • Load current file: ctrl+alt+c enter
  • Evaluate current form: ctrl+enter
  • Evaluate current top-level form: alt+enter
  • Clear inline evaluation result: esc
  • Copy last evaluation results: ctrl+alt+c ctrl+c

4 Other commands

You can find all commands in Feature Contributions in the Calva extension page. Commonly used commands:

  • Expand selection: ctrl+w

  • Shrink selection: ctrl+alt+w

  • Toggle pretty printing (on by default): ctrl+alt+c p

  • Run all tests: ctrl+alt+c alt+t

  • Run tests for current namespace: ctrl+alt+c t

  • Run current test: ctrl+alt+c ctrl+alt+t

  • Forward Sexp: ctrl+alt+right

  • Backward Sexp: ctrl+alt+left

  • Forward Down Sexp: ctrl+down

  • Forward up Sexp: ctrl+alt+down

  • Backward Down Sexp: ctrl+alt+up

  • Backward Up Sexp: ctrl+up

  • Delet Sexp forward: ctrl+shift+delete

  • Delete Sexp backward: ctrl+alt+backspace

  • Delete forward to end of list: ctrl+delete

  • Delete backward to start of list: ctrl+backspace

  • Show preivous REPL history entry: alt+up

  • Show next REPL history entry: alt+down