Language servers¶

ase speaks LSP over stdio. Point it at a server and you get diagnostics, completion, hover, go-to-definition, find-references and a document outline.

Linux and macOS only

The client spawns the server as a child process over stdio, and that path is not implemented on Windows — ase_process_spawn() returns nothing there, so the server never starts and :compile does nothing either. See ADR 0011, decision 6.

Setting one up¶

lsp_command = clangd              # for any language without its own
lang.python.lsp = pylsp           # for one language
lang.rust.lsp = rust-analyzer
lang.go.lsp = gopls

The language id is the same name used for highlighting, so a language with no Tree-sitter grammar still gets a server.

The status bar names the server when it is running, and says so when it failed or is not configured. A blank bar read as broken, so it is never blank.

What you get¶


`F12`	Go to definition (`gd` in Vim mode)
`Shift+F12`	Every use of the symbol under the cursor
`F2`	Rename the symbol everywhere, previewed before it happens
`Alt+S`	Outline of this file
hover	Hold still over a symbol
completion	As you type
diagnostics	Underlined, in the theme's own error and warning colours

Find-references and the document outline open the panel below the buffer. Ctrl+W j moves focus into it, Ctrl+J / Ctrl+K move through the results, Enter jumps — and keeps the keyboard in the panel, so you can walk a list of twenty references without reaching back for it each time.

Rename shows you every change first, across every file the server names — space keeps or drops one, Ctrl+Enter applies. The files it changes are opened as buffers and nothing is written until you save, so closing them without saving undoes the whole thing. See Replacing across files for the same preview, and ADR 0132 for why an edit the server describes in a way this editor cannot represent exactly is skipped rather than guessed at.

Ctrl+O and Ctrl+I go back and forward through the jumps you made.

Per project¶

One server per project per window, shared by every buffer in it, so opening a second file in the same repository does not start a second clangd.

The project root is the enclosing git checkout when there is one.

Suffixes¶

If a suffix means something other than the default — .h in a C++ project, say — tell the project rather than your global config:

# .ase.conf at the root of the project
filetype.h = cpp

That file may only set filetype.*, never a command to run. See Configuration.