grammar

I understand that the Perl syntax is ambiguous and that its disambiguation is non-trivial ( sometimes involving execution of code during the compile phase ). Regardless, does Perl have a formal grammar (albeit ambiguous and/or context-sensitive)? From perlfaq7 Can I get a BNF/yacc/RE for the Perl language? There is no BNF, but you can paw your way through the yacc grammar in perly.y in the source distribution if you're particularly brave. The grammar relies on very smart tokenizing code, so be prepared to venture into toke.c as well. In the words of Chaim Frenkel: "Perl's grammar can not be

I want to create a program that reads text from a file and points out when "a" and "an" is used incorrect. The general rule as far as I know is that "an" is used when the next words starts with a vowel. But it should also take into consideration that there are exceptions which also should be read from a file. Could someone give me some tips and tricks on how I should get started with this. Functions or so that could help. I would be very glad :-) I'm quite new to Python. jfs Here's a solution where correctness is defined as: an comes before a word that starts with a vowel sound, otherwise a

I'm trying to learn Parsec by implementing a small regular expression parser. In BNF, my grammar looks something like: EXP : EXP * | LIT EXP | LIT I've tried to implement this in Haskell as: expr = try star <|> try litE <|> lit litE = do c <- noneOf "*" rest <- expr return (c : rest) lit = do c <- noneOf "*" return [c] star = do content <- expr char '*' return (content ++ "*") There are some infinite loops here though (e.g. expr -> star -> expr without consuming any tokens) which makes the parser loop forever. I'm not really sure how to fix it though, because the very nature of star is that it

Is there an existing POSIX sh grammar available or do I have to figure it out from the specification directly? Note I'm not so much interested in a pure sh; an extended but conformant sh is also more than fine for my purposes. The POSIX standard defines the grammar for the POSIX shell. The definition includes an annotated Yacc grammar. As such, it can be converted to EBNF more or less mechanically. If you want a 'real' grammar, then you have to look harder. Choose your 'real shell' and find the source and work out what the grammar is from that. Note that EBNF is not used widely. It is of