WideFinder--Naive F# Implementation
Jomo Fisher--Here's an interesting problem that some people are having fun with. Don Box posted a naive implementation in C# so I thought I'd post the equivalent in F#:
#light
open System.Text.RegularExpressions
open System.IO
open System.Text
let regex = new Regex(@"GET /ongoing/When/\d\d\dx/(\d\d\d\d/\d\d/\d\d/[^ .]+)", RegexOptions.Compiled)
let seqRead fileName =
seq { use reader = new StreamReader(File.OpenRead(fileName))
while not reader.EndOfStream do
yield reader.ReadLine() }
let query fileName =
seqRead fileName
|> Seq.map (fun line -> regex.Match(line))
|> Seq.filter (fun regMatch -> regMatch.Success)
|> Seq.map (fun regMatch -> regMatch.Value)
|> Seq.countBy (fun url -> url)
And here's the code to call it:
for result in query @"file.txt" do
let url, count = result
One nice thing is that F#'s interactive window has a #time;; option which shows you wall-clock time and CPU time. Here is the result from running the code above on a 256meg file I concatenated together (I couldn't find the one Don was using):
Real: 00:00:06.899, CPU: 00:00:04.165, GC gen0: 416, gen1: 1, gen2: 0
It looks like the majority of the time is in CPU so there should be ample opportunity to parallelize. One thing to note: I think the interactive window is unoptimized--when I just compile and run the code, I get times in the sub 5-seconds range. My machine is a 4-way 2.4 GHz Core Duo.
This posting is provided "AS IS" with no warranties, and confers no rights.
