On Oct 2, 2007, at 9:52 , Alex Queiroz wrote:
(parseDottedList ls) <|> (parseProperList ls)
I've factored out the common left sub-expression in parseLeftList. The problem is that "..." is a valid identifier so when inside the left of the list the parser sees a single dot, it tries to match it with "...", which fails. Can anybody give advice on how to rewrite these list parsing functions?
try (parseDottedList ls) <|> parseProperList ls Overuse of try is a bad idea because it's slow, but sometimes it's the only way to go; it insures backtracking in cases like this. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH