You can get the VSCode extension for Lambdapi from the Marketplace. To install it from the sources, see INSTALL.md.

The extension provides syntax highlighting, go-to-definition, key-bindings for proof navigation, and snippets for inputing common mathematical symbols.

Logs (command debug) are displayed in a terminal which opens automatically when needed.


Make sure you have a lambdapi.pkg file in your folder when editing a Lambdapi file in it.

Proof navigation

Goals are visualised in a panel on the right side of the editor. You can navigate in proof with the following key-bindings:

  • Ctrl+Right: go one step forward

  • Ctrl+Left: go one step backward

  • Ctrl+Up: go to the previous proof (or the beginning)

  • Ctrl+Down: go to the next proof (or the end)

  • Ctrl+Enter: go to the position of the cursor

  • Ctrl+Alt+c: toggle cursor mode (proof highlight follows the cursor or not)

  • Ctrl+Alt+w: toggle follow mode (proof highlight is always centered in the window when keybindings are pressed)

  • Shift+Alt+w: center proof highlight in the current window

Hover and go-to-definition

Hovering a token will display its type if available. For the go-to-definition, you can either:

  • press F12 when the cursor is within the range of a certain symbol

  • or right-click on the symbol -> “Go to definition”. It is advised to set up a key-binding for “Go back” in File -> Preferences -> Keyboard shortcuts.


Type one of the suggested snippets described below, then press Enter or Tab to confirm adding the chosen Unicode character. If a snippet completion does not seem to work, try pressing Ctrl+Space to see completion suggestions.

Common symbols: `ra: →, `is: ≔, `re: ↪, `all: ∀, `ex: ∃, `imp: ⇒, `or : ∨, `and : ∧, `not : ¬, `th: ⊢, `eq: ≡, `box: □, `cons: ⸬

Greek letters: For every letter l, typing `l will suggest a corresponding unicode greek letter (for instance `b will suggest β). Some greek letters are present in a variant form as in LaTeX, accessible with `vl (for instance, `f will suggest ϕ and `vf will suggest φ).

Fonts: For every letter l, the following prefixes change the font of l: `dl for double-struck (ℕ), `il: italic (𝑁), `Il: bold italic (𝑵), `sl: script (𝒩 ), `Sl: bold script (𝓝), `fl: Fraktur (𝔑).

Recommended additional extension

  • unicode-math replaces -> by →, _1 by ₁, and many other unicode characters by simply pressing Tab.