Re: Parsec allocating a lot of memory

On Mon, 4 Aug 2003 19:16:44 +0200 Nick Name wrote:

Hi all, I am using "parsec" to parse the output from "xmame -listinfo" wich is a list of records of the form

game ( attr1 value1 ... attrN valueN )

and for approx. 3500 records I got ~250 mb of RSS memory during parsing, wich takes 20 seconds on my athlon 1400.

I think that I must have done something wrong (this is the first time I use parsec), here is my parser:

--- Begin games = many game

game => do openGame x <- manyTill attribute closeGame return (mkGameInfo x)

attribute = do whitespaces x <- identifier whitespaces y <- tillEOL return (x,y)

openGame = do string "game (" newline

closeGame = do string ")" newline newline

whitespace = "\v\f\t\r " whitespaces = skipMany (oneOf whitespace)

tillEOL = manyTill anyChar newline

identifier = many alphaNum --- End

Thanks for any advice

Vincenzo

I'm pretty sure the issue is the manyTill's. Using the Language and Token modules you can write this parser much more compactly and likely more efficiently. The Token combinators automatically handle whitespace which is very probably what you want. games = many game game = do symbol "game" attrs <- parens (many attribute) return (mkGameInfo attrs) attribute = do attr <- identifier val <- many (satisfy (not . ('\n'==))) spaces return (attr,val)