Treesitter Hoon Parser

Create a better hoon parser with Treesitter

May 11, 2023

Reward: 2 Stars

ID: P0263

Grantee(s): ~hosweg-silpur

Champion(s): ~poldec-tonteg

CompletedProposalDev: Core


Tree-sitter is a fast parser that supports smarter syntax highlighting that makes use of the syntax tree.


Current syntax-highlighters are based off complicated regex that are overly complicated and inaccurate. Tree-sitter parses the whole document and creates an abstract syntax tree (AST) which can then be used to correctly highlight syntax.

The current syntax highlighters available for hoon are:

  • Hoon-lsp: Decent, but due to being a semantic highlighter it naively highlights using regex matches. As an example it does not know the difference between !=(a) and !=(a 1). (The first is the zaptis rune taking a as a sample, the second is ! applied to an equality check between a and 1)

  • Hoon.vim/hoon-mode.el(emacs package): This is also a regex matcher and suffers from the same problems above.

In conclusion, creating a tree-sitter parser will allow for superior Hoon highlighting to be used in more code-editors.

Milestones and Compensation

Milestone 1: Writing the grammar

Estimated Completion: Completed

Payment: 1 star

  • Write a tree-sitter grammar that parses Hoon
  • Create unit tests for each syntax component (runes, irregular syntax, mold, strings...)

Milestone 2: Code editor Integration

Estimated Completion: May 2023

Payment: 1 star

Integrate the tree-sitter parser with various code-editors.

Desktop editors:

  • VScode
  • Emacs
  • Neovim
  • Atom Online editors:
  • Monaco
  • Codemirror

Future Work

  • GitHub Gist alternative on Urbit
  • Online IDE with %pyro sandbox
  • Collaborative Hoon code-editing with CRDTs