Daml Syntax Highlighting on Emacs

I have been using this daml-mode in Emacs and I find it quite good. Much thanks to @bartfaitamas who, as I understand it, is the author of this code.

These instructions also include an lsp-mode for Daml that I haven’t had a chance to play around with yet. When I do get a chance, hopefully I can write another tutorial on that. Or maybe somebody will beat me to it. :slightly_smiling_face:

First, create a directory ${HOME}/.emacs.d/lisp/daml-mode, and copy the following two files into that directory:

  1. daml-mode.el
  2. lsp-mode.el

Next, add the following snippet into your ${HOME}/.emacs file:

(use-package daml-mode
  :load-path "lisp/daml-mode/"
  :mode "\\.daml\'"
  :bind (:map daml-mode-map
         ("M-n" . flymake-goto-next-error)
         ("M-p" . flymake-goto-next-error)
         ("<tab>" . haskell-indent-cycle))
  :config
  (require 'lsp-daml)
  ;; (setq lsp-daml-extra-arguments '("--scenarios" "no" "--telemetry" "--ghc-option" "-XMonoLocalBinds" "--ghc-option" "-W" "--ghc-option" "-Wno-unused-binds" "--ghc-option" "-Wno-unused-matches" "--RTS" "--jobs" "16" "+RTS" "-N16" "-H10G" "-M12G" "-A20M" "-RTS"))
  )

Finally, restart your Emacs server. At this point, you should get syntax highlighting when you open up a .daml file in Emacs!

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@sully Great write-up.

Apart from installing Emacs & Lisp, this is simple and in one location.

Thank you :+1:t2:

P.S. What is the lag like when you demand highlighting in-code? Using VIM-LSP there is a noticeable lag, when the LSP Server is called to serve. Mildly annoying.

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Hey thanks @quidagis :blush:

I notice no lag for the daml-mode syntax highlighting. As far as the lsp-mode goes, I couldn’t tell you yet. I hope to get around to trying out the LSP at some point.

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The daml language server does not provide any form of syntax highlighting. That’s done on the client side by a bunch of regex specific to your editor. So it really shouldn’t introduce any lag in that regard.

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Maybe it should not, but on the 8 Core Desktop, everytime the LSP-Server would detect a Daml term, I could hear the noticeable difference in CPU, therefore CPU fan activity. About 1-3 seconds, then the Daml highlighting would render and the CPU activity would drop back to normal. Verified with Htop.

I was using the Daml-on-Vim config that I posted above. No wonder it is now Headless.

Maybe the vim setup blocks on something else. The language server literally has no code for syntax highlighting so it cannot be slow because of that.

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I had to make a couple of tweaks to the lsp mode file to get it working with lsp-mode 8. I’m not able to attach the modified file due to being a new user, but it can be found here: GitHub gist

Also, a backslash got eaten from the .emacs snippet posted above. Here is a repaired version:

(use-package daml-mode
  :load-path "/usr/local/share/emacs/site-lisp/daml-mode/"
  :mode "\\.daml\\'"
  :bind (:map daml-mode-map
         ("M-n" . flymake-goto-next-error)
         ("M-p" . flymake-goto-next-error)
         ("<tab>" . haskell-indent-cycle))
  :config
  (require 'lsp-daml)
)

By the way it would be nice if this package could be added to Melpa so it could be easily installed from Emacs directly via M-x package-install. This would entail putting the package itself somewhere publically accessible such as Github, and licensing it with a GPL-compatible license. As the original author, this part would be up to @bartfaitamas. If this were done, then in principle anyone could submit a “recipe” request to the Melpa repo, although in practice it’s preferred that the package author themselves do so.

@arobertn I’m trying to find some time this week to start cleaning my code up, make it public and submit it to melpa.

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Hello guys. I created a repo for this daml-mode here: GitHub - bartfailt/daml-mode

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Thank you for the writeup. This worked great on my emacs doom. The only modification I had to make was to the load-path to make fit into my setup.
:load-path "~/.emacs.d/lisp/daml-mode/"