On Tuesday 13 February 2007 15:59, Duncan Coutts wrote:
On Tue, 2007-02-13 at 15:27 -0500, Jefferson Heard wrote:
Hi, I am running the following code against a 210 MB file in an attempt to determine whether I should use alex or whether, since my needs are very performance oriented, I should write a lexer of my own. I thought that everything I'd written here was tail-recursive
Isn't that exactly the problem - that it's tail recursive? You do not want it to be tail recursive since then it must consume the whole input before producing any output. You want it to be as lazy as possible so that it can start producing tokens as soon as possible without having to consume everything.
If performance is really important to you then you may also want to investigate lexing from a lazy ByteString. Alex can now do that (darcs version) or you can do it by hand as you're trying now.
Duncan
Argh, bitten by the scheme bug! Right -- NO tail recursion... So that leaves me with some rather non-intuitive strategies for achieving execution time efficiency. Anyone care to point me in the direction of a document on efficiency in Haskell?