#Cognate Playground

Canonical instance: https://cognate-playground.hedy.dev/

An interactive playground for Cognate that uses a JavaScript implementation of Cognate.

It currently supports about 90% of all builtins from the C prelude, and all types except IO. Discrepancies of this implementation that can be illustrated by tests can be found with XFAIL markers in the tests directory.

Files of interest

• index.html
• cognate.js -- the parser, linter, and runtime
• main.js -- the rest of the app excluding the editor
• editor/* -- code relating to the editor component
• public/tree-sitter.{js,wasm} -- from tree-sitter releases
• public/tree-sitter-cognate.wasm -- built from tree-sitter-cognate
• public/prelude.cog -- definitions of various built-in functions. copied from the Cognate repo with only I/O builtins commented out. eventually it will simply link to the prelude.cog file from the Cognate repo.

#Todo

The runtime and cognate implementation

• [X] Working interpreter
• [X] Escape HTML
• [X] Proper "types"
• [X] Scoping
• [X] Support symbols and floats
• [X] Support Set (temporarily) to update values from outer scope
• [X] Function shadowing
• [X] Fix lexical scoping
• [X] Support List
• [X] Support hoisting
• [X] Allow shadowing things in the prelude and builtins
• [X] Fix Print; Add Show
• [X] Update Prelude from upstream
• [X] Add Stack
• [X] Add string methods
• [X] Support Box and a proper Set
• [X] String escape sequences
• [X] Prevent stack overflows
• [ ] Explore optimization options, consider feasibility of transpiling to JS or using bytecode
• [X] Standard library coverage
• [X] Closures
• [X] Tests
• [ ] Consider using something like decimal.js for floating point precision
• [ ] Mock I/O
• [X] Table

The Playground

• [X] Presets of example code
• [X] Save input in localstorage
• [X] Live syntax highlighting
• [X] [perf] Collect all tokens to be highlighted, and dispatch them in batch
• [X] [perf] Avoid re-evaluating the prelude each time
• [X] [perf] Send edits to tree-sitter instead
• [ ] Use worker thread for the runtime
• [ ] Allow stopping current execution with a button
• [ ] Auto-eval after a timeout, merging several successive edits in one
• [X] (1) Highlight references of functions in scope
• [X] Show parser errors inline in the editor
• [ ] More informative runtime errors
  • [ ] Format the traceback similar to Python (or Web Console)
  • [ ] Collapse recursive calls and show surrounding code(?)
  • [ ] Clicks on symbols can navigate to the definition/reference in the editor
• [X] Fix (1); highlight with static analysis rather than at runtime
• [ ] [perf] Find ways to accurately cache for (1)
• [X] Handle failure to fetch prelude
• [X] Fix tree-sitter edit conversions for pair wrapping (editor feature)
• [ ] Editor settings
  • [ ] Tooltip hints
  • [ ] Autocomplete
  • [ ] Tab handling
  • [ ] Auto eval - if not, show a Run button
• [ ] Lint for possible missing semicolons
• [ ] Special function, (or just Print) that allows exploring data structures interactively (similar to the Web Console) - but retain cognac behaviour with Show