Code completions for Racket or Scheme

[ZovutVanya]

I am completely new to all the lisp stuff and relatively new to neovim. I am now working through the SICP book and for that reason got into the Scheme/Racket (my options are mit-scheme in WSL and Racket with #lang sicp on Windows)
My main question is on completions. Conjure says it supports completions through several plugins, I use nvim-cmp, and for that the cmp-conjure plugin is suggested. But I still don't have completions after setting it up. Maybe the completions are only supported for the more popular lisps like Clojure? I just am not aware how to know for sure
If there are ways to add completions for Racket or Scheme with conjure, please let me know!
My lazy setup is straight from the conjure github:

return {
  { "wlangstroth/vim-racket",
    ft = "racket",
  },
  {
    "Olical/conjure",
    ft = { "racket", "scheme", "clojure" }, -- etc
    lazy = true,
    init = function()
      -- Set configuration options here
      -- Uncomment this to get verbose logging to help diagnose internal Conjure issues
      -- This is VERY helpful when reporting an issue with the project
      -- vim.g["conjure#debug"] = true
    end,

    -- Optional cmp-conjure integration
    dependencies = { "PaterJason/cmp-conjure" },
  },
  {
    "PaterJason/cmp-conjure",
    lazy = true,
    config = function()
      local cmp = require("cmp")
      local config = cmp.get_config()
      table.insert(config.sources, { name = "conjure" })
      return cmp.setup(config)
    end,
  },
}

[Olical]

Yes I'm afraid that completion support requires each client to implement a function that provides the completions in that language. Depending on the client this ranges from trivial to impossible to implement. The client feature matrix can be found here, it may well have drifted out of sync though (corrections are appreciated!) https://github.com/Olical/conjure/wiki/Client-features

The last section of :help conjure talks about the client API shape and the completion function, so if anyone wants to help implement completions for a particular client I'd be happy to try and help or guide them. It's just a single function, it's just hard to work out how to turn that completion request into good results in every client / language.

[ZovutVanya]

Thanks for the answer, haven't found the matrix! And thanks for the plugin, still gonna use it, having great experience with it even without completions!
Hopefully, someone will do the func, or just give me a couple of years, will finish sicp and come back here :)

[russtoku]

To restate what @Olical answered, cmp-conjure calls the completions function of the Conjure client for the program source being edited. With the completions function implemented, cmp-conjure can respond appropriately.

For anyone who would like to implement completions for Conjure clients, the wiki page on Client Features says:

The Aniseed client is a good example of this system despite it’s complexities. It’s doing a lot of work to evaluate chunks of code to attempt to pull values out of the local scope and peek into tables to get their keys but I think it’ll show you everything that needs to be done.

I tried to do this for the Common List client but it needs a bit more testing and feedback from people who use that client. The Common List client needs much more love, too, but that's another story.

For the Racket and the Scheme clients, implementing the completions function would have the client function call a "symbol completion" module in the Racket or Scheme REPL. The results from that would be packaged up by the client function and returned via the usual Conjure and Neovim mechanism.

I'm a total newbie to Scheme and Racket so I'm guessing about what a completions module for Scheme would be but a quick web search suggests these as possible starting points to dive into:

• Scheme mode
  - Section 8.3 of https://www.gnu.org/software/mit-scheme/documentation/stable/mit-scheme-user.html
  - https://alexott.net/en/writings/emacs-devenv/EmacsScheme.html
• scheme-complete
• https://www.nongnu.org/geiser/The-REPL.html#Completion-and-error-handling

[russtoku]

@ZovutVanya, you said that you have nvim-cmp set up. If you also have nvim-lspconfig, you can configure a language server for Racket or Scheme to handle completions instead of relying on the Racket or Scheme clients in Conjure. https://github.com/neovim/nvim-lspconfig should help guide you. https://github.com/williamboman/mason.nvim can provide an easy way to get the Racket and Scheme language servers set up if you decide to use either one of them.

In the #racket channel in the Conjure Discord, @AAA1exa8 shared his configuration for Neovim plugins for use with Racket.

[ZovutVanya]

Thanks, I will look into that!