If you can parse "do x == y == z" or "case 0 of x -> x == x == True" you're probably ok. I can't tell from your example if this works or not. -- Lennart Doaitse Swierstra wrote:
On 2006 mrt 09, at 1:54, Lennart Augustsson wrote:
I agree with it being complicated. I don't know of any compiler that implements it correctly. Do you say your combinators do?
At least we think so. The way to use it is e.g.:
pExprPrefix = sem_Expr_Let <$ pKey "let" <*> pDecls <* pKey "in"
pDecls = foldr sem_Decls_Cons sem_Decls_Nil <$> pBlock pOCurly pSemi pCCurly pDecl
pDecl = sem_Decl_Val <$> pPatExprBase <* pKey "=" <*> pExpr <|> sem_Decl_TySig <$> pVar <* pKey "::" <*> pTyExpr
in which the pBlock takes care of the offside rule, in cooperation with the scanner.
That said, I don't think it can be replaced easily without breaking existing code, so I'm unwilling to change unless someone can show an alternative that handles 99.9% of the existing code.
There are solutions to this kind of transitions. Compilers could admit the old rule, and emit a warning when e.g. the --this-is-supposed-to-be-strictly-haskell-prime flag is passed. One might also equip a compiler to transform one's program into the new standard.
Doaitse