[Haskell-cafe] GHC 7.10 GHC-API Changes and proposed changes.

[Alan & Kim Zimmerman]

There are a number of changes in GHC 7.10 that will make it easier for
tool writers to use the GHC API.

These include

1. More parser entrypoints, to explicitly parse fragments [Andrew Gibiansky]

  The following parsers are now provided

    parseModule, parseImport, parseStatement, ​ parseDeclaration,
    parseExpression, parseTypeSignature, ​ parseFullStmt, parseStmt,
    parseIdentifier, ​ parseType, parseHeader

2. No more landmines in the AST [Alan Zimmerman]

  In the past it was difficult to work with the GHC AST as any generic
  traversals had to carefully tiptoe around an assortment of panic and
  undefined expressions. These have now been removed, allowing
  standard traversal libraries to be used.

There is a third change currently being discussed, and I would like
feedback on it's desirability.

3. Introduce an annotation structure to the ParsedSource to record the
location of uncaptured keywords.

  At the moment the location of let / in / if / then / else / do
  etc is not captured in the AST. This makes it difficult to
  parse some source, transform the AST, and then output it again
  preserving the original layout.

  The current proposal, which can be seen at [1] and a proof of
  concept implementation at [2] returns a structure keyed to each AST
  element containing simply the specific SrcSpan's not already
  captured in the AST.

  This is the analogue of the Language.Haskell.Exts.Annotated.Syntax
  from haskell-src-exts, except a custom SrcSpanInfo structure is
  provided for each AST element constructor, and it is not embedded
  within the AST.

  [1] https://ghc.haskell.org/trac/ghc/wiki/GhcAstAnnotations
  [2] https://phabricator.haskell.org/D297

So, apart from HaRe, are there any other users who would be interested
in using this?

Regards
  Alan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20141001/c2587307/attachment.html>