Language Server Protocol implementation for Nim


Nim Language Server Protocol

This is a Language Server Protocol implementation in Nim, for Nim. It is based on nimsuggest, which means that every editor that supports LSP will now have the same quality of suggestions that has previously only been available in supported editors.

Installing nimlsp

The easiest way to install nimlsp is to use nimble with:

nimble install nimlsp

This will compile and install it in the nimble binary directory, which if you've set it up correctly should be in your path. When using nimlsp it needs to have Nims sources available to know the types in the standard library. This defaults to something that should work with the regular installation, but you can set it on compile-time with -d:explicitSourcePath=PATH, or on runtime by supplying it as an argument to nimlsp. How exectly to do that will depend on the LSP client.

Compile nimlsp

If you want more control over the compilation feel free to clone the repository. nimlsp depends on the nimsuggest sources which is in the main Nim repository. This means you can either clone the Nim repository with

git submodule update --init --recursive

Or if you don't want a full clone of the Nim sources you can copy just the nimsuggest folder into the Nim folder in src/nimlsppkg. This means the default source path will not work as well so either set it explicitly on compilation with -d:explicitSourcePath=PATH or on runtime.

To do the standard build run:

nimble build

Or if you want debug output when nimlsp is running:

nimble debug

Supported Protocol features

Status LSP Command
☑ DONE textDocument/didChange
☑ DONE textDocument/didClose
☑ DONE textDocument/didOpen
☑ DONE textDocument/didSave
☐ TODO textDocument/codeAction
☑ DONE textDocument/completion
☑ DONE textDocument/definition
☐ TODO textDocument/documentHighlight
☐ TODO textDocument/documentSymbol
☐ TODO textDocument/executeCommand
☐ TODO textDocument/format
☑ DONE textDocument/hover
☑ DONE textDocument/rename
☑ DONE textDocument/references
☐ TODO textDocument/signatureHelp
☑ DONE textDocument/publishDiagnostics
☐ TODO workspace/symbol

Setting up nimlsp


First you need a LSP client, the one that's been tested is It's certainly not perfect, but it works well enough.

Once you have it installed you'll want to grab NimLime as well. NimLime can perform many of the same features that nimlsp does, but we're only interested in syntax highlighting and some definitions. If you know how to disable the overlapping features or achieve this in another way please update this section.

Now in order to set up LSP itself enter it's settings and add this:

            "<path to nimlsp>/nimlsp" // This can be changed if you put nimlsp in your PATH
         "enabled": true,
            "PATH": "<home directory>/.nimble/bin" // To be able to find nimsuggest, can be changed if you have nimsuggest in your PATH
         "languageId": "nim",
   // These are mostly for debugging feel free to remove them
   // If you build nimlsp without debug information it doesn't
   // write anything to stderr
   "log_payloads": true,
   "log_stderr": true


To use nimlsp in Vim install the prabirshrestha/vim-lsp plugin and dependencies:

Plugin 'prabirshrestha/asyncomplete.vim'
Plugin 'prabirshrestha/async.vim'
Plugin 'prabirshrestha/vim-lsp'
Plugin 'prabirshrestha/asyncomplete-lsp.vim'

Then set it up to use nimlsp for Nim files:

if executable('nimlsp')
   au User lsp_setup call lsp#register_server({
     \ 'name': 'nimlsp',
     \ 'cmd': {server_info->['nimlsp']},
     \ 'whitelist': ['nim'],
     \ })

let g:lsp_log_verbose = 1
let g:lsp_log_file = expand('/tmp/vim-lsp.log')

" for asyncomplete.vim log
let g:asyncomplete_log_file = expand('/tmp/asyncomplete.log')

let g:asyncomplete_auto_popup = 0

function! s:check_back_space() abort
    let col = col('.') - 1
    return !col || getline('.')[col - 1]  =~ '\s'

inoremap <silent><expr> <TAB>
  \ pumvisible() ? "\<C-n>" :
  \ <SID>check_back_space() ? "\<TAB>" :
  \ asyncomplete#force_refresh()
inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"

This configuration allows you to hit Tab to get auto-complete, and to call various functions to rename and get definitions. Of course you are free to configure this any way you'd like.

Run Tests

Not too many at the moment unfortunately, but they can be run with:

nimble test
Need help? Read Nimble
Available versions:
License: MIT

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