Lossless Syntax Tree Pattern

Hacker News Comments on "From AST to Lossless Syntax Tree"

Other Names

• RedBaron: Full Syntax Tree
• Go: AST
• Roslyn: Syntax Tree
  • Red-Green Trees? TODO: read this

Relevant Docs / Designs / Discussions

• Roslyn -- Microsoft's C# compiler platform

• Haskell GHC AST Annotations -- Simplify the roundtripping and modification of source by explicitly capturing the missing location information for the syntactic markers

• Making Tools Kythe-Compatible -- I would have thought that Kythe had the LST concept, because it's basically an IDE, but I don't see it. I guess that is because it's read-only?

• What to do about comments? on Lambda the Ultimate

Style-Preserving Source Translators

• 2to3 -- for Python 2 to Python 3
• RedBaron -- RedBaron, by relying on Baron, uses a Full Syntax Tree (FST). It’s like an AST except it keeps every information, included formatting, and is then a lossless representation of the source code.

Source Reformatters

TODO: What data structures do these use?

• clang-format -- Clang AST, which is huge
  • http://clang.llvm.org/docs/LibFormat.html -- design is undocumented
• gofmt -- uses the Go AST package, which is reputed to be messy
• dartfmt -- The Hardest Program I've Ever Written
• yapf for Python
• scalafmt
• prettier for JavaScript
• rustfmt Design -- Blog Post

Transpilers

These don't need to use the Lossless Syntax Tree because the resulting code won't be edited by a human.

• CoffeeScript, etc.