A language server for Fennel. Supports Go-to-definition, and a little bit of completion suggestions. Fennel-LS uses static analysis, and does not execute your code.
You can ask fennel-ls to treat your file as a macro file if the first line
exactly matches ;; fennel-ls: macro-file
. Expect this to change at some point
in the future when I come up with a better way to specify which files are meant
to be macro files.
I recommend building from source. I promise it's really easy! You need to have make
and lua
(5.1+). Every other dependency is included. See the License section at the bottom of this file for more info on the bundled dependencies.
make && sudo make install
make install PREFIX=$HOME
make
If you are using NixOS, you can use the included /flake.nix
or /default.nix
.
I recommend just using make
if possible, but if not, fennel-ls
can be built with LuaRocks.
luarocks install fennel-ls --tree /path/to/your/new/luarocks/tree
Once you've installed the binary somewhere on your computer, the next step is to set up your text editor! Each editor has a different way of doing it.
If you are using vim+lspconfig, it is pretty simple:
require('lspconfig').fennel_ls.setup()
For Emacs, (eglot, built-in to 29+):
(with-eval-after-load 'eglot
(add-to-list 'eglot-server-programs '(fennel-mode . ("fennel-ls"))))
It should be possible to set up for other text editors, but the instructions depend on which editor you use. Generally you need to give this information to your editor:
- "fennel-ls" is a language server program on the $PATH
- it should be run for .fnl files.
You can gather diagnostics without connecting your editor:
fennel-ls --check my-file.fnl f2.fnl # prints diagnostics for the files given
This will analyze the given files, and print out all compiler errors and lints.
fennel-ls can be configured over LSP. Any setting that's not provided will be filled in with the defaults, which means that {}
will be a valid configuration with default settings. You can provide different settings in the same shape as the default settings in order to override the defaults.
fennel-ls default settings:
{
"fennel-ls": {
"fennel-path": "./?.fnl;./?/init.fnl;src/?.fnl;src/?/init.fnl",
"macro-path": "./?.fnl;./?/init-macros.fnl;./?/init.fnl;src/?.fnl;src/?/init-macros.fnl;src/?/init.fnl",
"checks": {
"unused-definition": true,
"unknown-module-field": true,
"unnecessary-method": true,
"bad-unpack": true,
"var-never-set": true,
"op-with-no-arguments": true,
"multival-in-middle-of-call": true
},
"extra-globals": ""
}
}
extra-globals : Space separated list of allowed global identifiers; in addition to a set of predefined lua globals.
Your editor can send these settings using one of these two methods:
- The client sends an
initialize
request with the structure{initializationOptions: {"fennel-ls": {...}}, ...}
- The client sends a
workspace/didChangeConfiguration
notfication containing the field{settings: {"fennel-ls": {YOUR_SETTINGS}}}
You can't load external lint rules with fennel-ls, but I would love to receive patches that add new lint rules! Instructions to add a lint.
fennel-ls is licensed under the MIT license. See LICENSE for more info. This project also contains files from other projects:
- test/pl/* comes from Penlight [MIT license]
- src/fennel-ls/json/* is modified, but is originally from json.lua [MIT license]
- src/fennel-ls/docs/* contains information from the lua reference [MIT license]
- test/faith/faith.lua is from faith [MIT license]
- fennel and src/fennel.lua are compiled from fennel [MIT license]